Kernel

          
            
# File tmp/rubies/ruby-2.6.10/lib/uri/common.rb, line 733
def URI(uri)
  if uri.is_a?(URI::Generic)
    uri
  elsif uri = String.try_convert(uri)
    URI.parse(uri)
  else
    raise ArgumentError,
      "bad argument (expected URI object or URI string)"
  end
end

          
        

Returns uri converted to an URI object.

          
            
static VALUE
rb_f_open(int argc, VALUE *argv)
{
    ID to_open = 0;
    int redirect = FALSE;

    if (argc >= 1) {
        CONST_ID(to_open, "to_open");
        if (rb_respond_to(argv[0], to_open)) {
            redirect = TRUE;
        }
        else {
            VALUE tmp = argv[0];
            FilePathValue(tmp);
            if (NIL_P(tmp)) {
                redirect = TRUE;
            }
            else {
                VALUE cmd = check_pipe_command(tmp);
                if (!NIL_P(cmd)) {
                    argv[0] = cmd;
                    return rb_io_s_popen(argc, argv, rb_cIO);
                }
            }
        }
    }
    if (redirect) {
        VALUE io = rb_funcallv(argv[0], to_open, argc-1, argv+1);

        if (rb_block_given_p()) {
            return rb_ensure(rb_yield, io, io_close, io);
        }
        return io;
    }
    return rb_io_s_open(argc, argv, rb_cFile);
}

          
        

Creates an IO object connected to the given stream, file, or subprocess.

If path does not start with a pipe character (|), treat it as the name of a file to open using the specified mode (defaulting to “r”).

The mode is either a string or an integer. If it is an integer, it must be bitwise-or of open(2) flags, such as File::RDWR or File::EXCL. If it is a string, it is either “fmode”, “fmode:ext_enc”, or “fmode:ext_enc:int_enc”.

See the documentation of IO.new for full documentation of the mode string directives.

If a file is being created, its initial permissions may be set using the perm parameter. See File.new and the open(2) and chmod(2) man pages for a description of permissions.

If a block is specified, it will be invoked with the IO object as a parameter, and the IO will be automatically closed when the block terminates. The call returns the value of the block.

If path starts with a pipe character ("|"), a subprocess is created, connected to the caller by a pair of pipes. The returned IO object may be used to write to the standard input and read from the standard output of this subprocess.

If the command following the pipe is a single minus sign ("|-"), Ruby forks, and this subprocess is connected to the parent. If the command is not "-", the subprocess runs the command.

When the subprocess is Ruby (opened via "|-"), the open call returns nil. If a block is associated with the open call, that block will run twice — once in the parent and once in the child.

The block parameter will be an IO object in the parent and nil in the child. The parent’s IO object will be connected to the child’s $stdin and $stdout. The subprocess will be terminated at the end of the block.

Examples

Reading from “testfile”:

open("testfile") do |f|
  print f.gets
end

Produces:

This is line one

Open a subprocess and read its output:

cmd = open("|date")
print cmd.gets
cmd.close

Produces:

Wed Apr  9 08:56:31 CDT 2003

Open a subprocess running the same Ruby program:

f = open("|-", "w+")
if f.nil?
  puts "in Child"
  exit
else
  puts "Got: #{f.gets}"
end

Produces:

Got: in Child

Open a subprocess using a block to receive the IO object:

open "|-" do |f|
  if f then
    # parent process
    puts "Got: #{f.gets}"
  else
    # child process
    puts "in Child"
  end
end

Produces:

Got: in Child

          
            
# File tmp/rubies/ruby-2.6.10/lib/pp.rb, line 582
def pp(*objs)
  objs.each {|obj|
    PP.pp(obj)
  }
  objs.size <= 1 ? objs.first : objs
end

          
        

prints arguments in pretty form.

pp returns argument(s).

          
            
static VALUE
rb_f_array(VALUE obj, VALUE arg)
{
    return rb_Array(arg);
}

          
        

Returns arg as an Array.

First tries to call to_ary on arg, then to_a. If arg does not respond to to_ary or to_a, returns an Array of length 1 containing arg.

If to_ary or to_a returns something other than an Array, raises a TypeError.

Array(["a", "b"])  #=> ["a", "b"]
Array(1..5)        #=> [1, 2, 3, 4, 5]
Array(key: :value) #=> [[:key, :value]]
Array(nil)         #=> []
Array(1)           #=> [1]

          
            
static VALUE
f_BigDecimal(int argc, VALUE *argv, VALUE self)
{
    ENTER(1);
    Real *pv;
    VALUE obj;

    obj = TypedData_Wrap_Struct(rb_cBigDecimal, &BigDecimal_data_type, 0);
    pv = BigDecimal_new(argc, argv);
    if (pv == NULL) return Qnil;
    SAVE(pv);
    if (ToValue(pv)) pv = VpCopy(NULL, pv);
    RTYPEDDATA_DATA(obj) = pv;
    RB_OBJ_FREEZE(obj);
    return pv->obj = obj;
}

          
        

Create a new BigDecimal object.

initial

The initial value, as an Integer, a Float, a Rational, a BigDecimal, or a String.

If it is a String, spaces are ignored and unrecognized characters terminate the value.

digits

The number of significant digits, as an Integer. If omitted or 0, the number of significant digits is determined from the initial value.

The actual number of significant digits used in computation is usually larger than the specified number.

exception

Whether an exception should be raised on invalid arguments. true by default, if passed false, just returns nil for invalid.

Exceptions

TypeError

If the initial type is neither Integer, Float, Rational, nor BigDecimal, this exception is raised.

TypeError

If the digits is not an Integer, this exception is raised.

ArgumentError

If initial is a Float, and the digits is larger than Float::DIG + 1, this exception is raised.

ArgumentError

If the initial is a Float or Rational, and the digits value is omitted, this exception is raised.

          
            
static VALUE
nucomp_f_complex(int argc, VALUE *argv, VALUE klass)
{
    VALUE a1, a2, opts = Qnil;
    int raise = TRUE;

    if (rb_scan_args(argc, argv, "11:", &a1, &a2, &opts) == 1) {
        a2 = Qundef;
    }
    if (!NIL_P(opts)) {
        static ID kwds[1];
        VALUE exception;
        if (!kwds[0]) {
            kwds[0] = idException;
        }
        rb_get_kwargs(opts, kwds, 0, 1, &exception);
        raise = (exception != Qfalse);
    }
    return nucomp_convert(rb_cComplex, a1, a2, raise);
}

          
        

Returns x+i*y;

Complex(1, 2)    #=> (1+2i)
Complex('1+2i')  #=> (1+2i)
Complex(nil)     #=> TypeError
Complex(1, nil)  #=> TypeError

Complex(1, nil, exception: false)  #=> nil
Complex('1+2', exception: false)   #=> nil

Syntax of string form:

string form = extra spaces , complex , extra spaces ;
complex = real part | [ sign ] , imaginary part
        | real part , sign , imaginary part
        | rational , "@" , rational ;
real part = rational ;
imaginary part = imaginary unit | unsigned rational , imaginary unit ;
rational = [ sign ] , unsigned rational ;
unsigned rational = numerator | numerator , "/" , denominator ;
numerator = integer part | fractional part | integer part , fractional part ;
denominator = digits ;
integer part = digits ;
fractional part = "." , digits , [ ( "e" | "E" ) , [ sign ] , digits ] ;
imaginary unit = "i" | "I" | "j" | "J" ;
sign = "-" | "+" ;
digits = digit , { digit | "_" , digit };
digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
extra spaces = ? \s* ? ;

See String#to_c.

          
            
static VALUE
rb_f_float(int argc, VALUE *argv, VALUE obj)
{
    VALUE arg = Qnil, opts = Qnil;

    rb_scan_args(argc, argv, "1:", &arg, &opts);
    return rb_convert_to_float(arg, opts_exception_p(opts));
}

          
        

Returns arg converted to a float. Numeric types are converted directly, and with exception to string and nil the rest are converted using arg.to_f. Converting a string with invalid characters will result in a ArgumentError. Converting nil generates a TypeError. Exceptions can be suppressed by passing exception: false.

Float(1)                 #=> 1.0
Float("123.456")         #=> 123.456
Float("123.0_badstring") #=> ArgumentError: invalid value for Float(): "123.0_badstring"
Float(nil)               #=> TypeError: can't convert nil into Float
Float("123.0_badstring", exception: false)  #=> nil

          
            
static VALUE
rb_f_hash(VALUE obj, VALUE arg)
{
    return rb_Hash(arg);
}

          
        

Converts arg to a Hash by calling arg.to_hash. Returns an empty Hash when arg is nil or [].

Hash([])          #=> {}
Hash(nil)         #=> {}
Hash(key: :value) #=> {:key => :value}
Hash([1, 2, 3])   #=> TypeError

          
            
static VALUE
rb_f_integer(int argc, VALUE *argv, VALUE obj)
{
    VALUE arg = Qnil, opts = Qnil;
    int base = 0;

    if (argc > 1) {
        int narg = 1;
        VALUE vbase = rb_check_to_int(argv[1]);
        if (!NIL_P(vbase)) {
            base = NUM2INT(vbase);
            narg = 2;
        }
        if (argc > narg) {
            VALUE hash = rb_check_hash_type(argv[argc-1]);
            if (!NIL_P(hash)) {
                opts = rb_extract_keywords(&hash);
                if (!hash) --argc;
            }
        }
    }
    rb_check_arity(argc, 1, 2);
    arg = argv[0];

    return rb_convert_to_integer(arg, base, opts_exception_p(opts));
}

          
        

Converts arg to an Integer. Numeric types are converted directly (with floating point numbers being truncated). base (0, or between 2 and 36) is a base for integer string representation. If arg is a String, when base is omitted or equals zero, radix indicators (0, 0b, and 0x) are honored. In any case, strings should be strictly conformed to numeric representation. This behavior is different from that of String#to_i. Non string values will be converted by first trying to_int, then to_i.

Passing nil raises a TypeError, while passing a String that does not conform with numeric representation raises an ArgumentError. This behavior can be altered by passing exception: false, in this case a not convertible value will return nil.

Integer(123.999)    #=> 123
Integer("0x1a")     #=> 26
Integer(Time.new)   #=> 1204973019
Integer("0930", 10) #=> 930
Integer("111", 2)   #=> 7
Integer(nil)        #=> TypeError: can't convert nil into Integer
Integer("x")        #=> ArgumentError: invalid value for Integer(): "x"

Integer("x", exception: false)        #=> nil

          
            
# File tmp/rubies/ruby-2.6.10/ext/json/lib/json/common.rb, line 438
def JSON(object, *args)
  if object.respond_to? :to_str
    JSON.parse(object.to_str, args.first)
  else
    JSON.generate(object, args.first)
  end
end

          
        

If object is string-like, parse the string and return the parsed result as a Ruby data structure. Otherwise, generate a JSON text from the Ruby data structure object and return it.

The opts argument is passed through to generate/parse respectively. See generate and parse for their documentation.

          
            
static VALUE
path_f_pathname(VALUE self, VALUE str)
{
    return rb_class_new_instance(1, &str, rb_cPathname);
}

          
        

Creates a new Pathname object from the given string, path, and returns pathname object.

In order to use this constructor, you must first require the Pathname standard library extension.

require 'pathname'
Pathname("/home/zzak")
#=> #<Pathname:/home/zzak>

See also Pathname::new for more information.

          
            
static VALUE
nurat_f_rational(int argc, VALUE *argv, VALUE klass)
{
    VALUE a1, a2, opts = Qnil;
    int raise = TRUE;

    if (rb_scan_args(argc, argv, "11:", &a1, &a2, &opts) == 1) {
        a2 = Qundef;
    }
    if (!NIL_P(opts)) {
        static ID kwds[1];
        VALUE exception;
        if (!kwds[0]) {
            kwds[0] = idException;
        }
        rb_get_kwargs(opts, kwds, 0, 1, &exception);
        raise = (exception != Qfalse);
    }
    return nurat_convert(rb_cRational, a1, a2, raise);
}

          
        

Returns x/y or arg as a Rational.

Rational(2, 3)   #=> (2/3)
Rational(5)      #=> (5/1)
Rational(0.5)    #=> (1/2)
Rational(0.3)    #=> (5404319552844595/18014398509481984)

Rational("2/3")  #=> (2/3)
Rational("0.3")  #=> (3/10)

Rational("10 cents")  #=> ArgumentError
Rational(nil)         #=> TypeError
Rational(1, nil)      #=> TypeError

Rational("10 cents", exception: false)  #=> nil

Syntax of the string form:

string form = extra spaces , rational , extra spaces ;
rational = [ sign ] , unsigned rational ;
unsigned rational = numerator | numerator , "/" , denominator ;
numerator = integer part | fractional part | integer part , fractional part ;
denominator = digits ;
integer part = digits ;
fractional part = "." , digits , [ ( "e" | "E" ) , [ sign ] , digits ] ;
sign = "-" | "+" ;
digits = digit , { digit | "_" , digit } ;
digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
extra spaces = ? \s* ? ;

See also String#to_r.

          
            
static VALUE
rb_f_string(VALUE obj, VALUE arg)
{
    return rb_String(arg);
}

          
        

Returns arg as a String.

First tries to call its to_str method, then its to_s method.

String(self)        #=> "main"
String(self.class)  #=> "Object"
String(123456)      #=> "123456"

          
            
# File tmp/rubies/ruby-2.6.10/lib/uri/common.rb, line 733
def URI(uri)
  if uri.is_a?(URI::Generic)
    uri
  elsif uri = String.try_convert(uri)
    URI.parse(uri)
  else
    raise ArgumentError,
      "bad argument (expected URI object or URI string)"
  end
end

          
        

Returns uri converted to an URI object.

          
            
static VALUE
rb_f_callee_name(void)
{
    ID fname = prev_frame_callee(); /* need *callee* ID */

    if (fname) {
        return ID2SYM(fname);
    }
    else {
        return Qnil;
    }
}

          
        

Returns the called name of the current method as a Symbol. If called outside of a method, it returns nil.

          
            
static VALUE
f_current_dirname(void)
{
    VALUE base = rb_current_realfilepath();
    if (NIL_P(base)) {
        return Qnil;
    }
    base = rb_file_dirname(base);
    return base;
}

          
        

Returns the canonicalized absolute path of the directory of the file from which this method is called. It means symlinks in the path is resolved. If __FILE__ is nil, it returns nil. The return value equals to File.dirname(File.realpath(__FILE__)).

          
            
static VALUE
rb_f_method_name(void)
{
    ID fname = prev_frame_func(); /* need *method* ID */

    if (fname) {
        return ID2SYM(fname);
    }
    else {
        return Qnil;
    }
}

          
        

Returns the name at the definition of the current method as a Symbol. If called outside of a method, it returns nil.

          
            
static VALUE
rb_f_backquote(VALUE obj, VALUE str)
{
    VALUE port;
    VALUE result;
    rb_io_t *fptr;

    SafeStringValue(str);
    rb_last_status_clear();
    port = pipe_open_s(str, "r", FMODE_READABLE|DEFAULT_TEXTMODE, NULL);
    if (NIL_P(port)) return rb_str_new(0,0);

    GetOpenFile(port, fptr);
    result = read_all(fptr, remain_size(fptr), Qnil);
    rb_io_close(port);
    RFILE(port)->fptr = NULL;
    rb_io_fptr_finalize(fptr);
    rb_gc_force_recycle(port); /* also guards from premature GC */

    return result;
}

          
        

Returns the standard output of running cmd in a subshell. The built-in syntax %x{...} uses this method. Sets $? to the process status.

`date`                   #=> "Wed Apr  9 08:56:30 CDT 2003\n"
`ls testdir`.split[1]    #=> "main.rb"
`echo oops && exit 99`   #=> "oops\n"
$?.exitstatus            #=> 99

          
            
VALUE
rb_f_abort(int argc, const VALUE *argv)
{
    rb_check_arity(argc, 0, 1);
    if (argc == 0) {
        rb_execution_context_t *ec = GET_EC();
        VALUE errinfo = ec->errinfo;
        if (!NIL_P(errinfo)) {
            rb_ec_error_print(ec, errinfo);
        }
        rb_exit(EXIT_FAILURE);
    }
    else {
        VALUE args[2];

        args[1] = args[0] = argv[0];
        StringValue(args[0]);
        rb_io_puts(1, args, rb_stderr);
        args[0] = INT2NUM(EXIT_FAILURE);
        rb_exc_raise(rb_class_new_instance(2, args, rb_eSystemExit));
    }

    UNREACHABLE_RETURN(Qnil);
}

          
        

Terminate execution immediately, effectively by calling Kernel.exit(false). If msg is given, it is written to STDERR prior to terminating.

          
            
static VALUE
rb_f_at_exit(void)
{
    VALUE proc;

    if (!rb_block_given_p()) {
        rb_raise(rb_eArgError, "called without a block");
    }
    proc = rb_block_proc();
    rb_set_end_proc(rb_call_end_proc, proc);
    return proc;
}

          
        

Converts block to a Proc object (and therefore binds it at the point of call) and registers it for execution when the program exits. If multiple handlers are registered, they are executed in reverse order of registration.

def do_at_exit(str1)
  at_exit { print str1 }
end
at_exit { puts "cruel world" }
do_at_exit("goodbye ")
exit

produces:

goodbye cruel world

          
            
static VALUE
rb_f_autoload(VALUE obj, VALUE sym, VALUE file)
{
    VALUE klass = rb_class_real(rb_vm_cbase());
    if (NIL_P(klass)) {
        rb_raise(rb_eTypeError, "Can not set autoload on singleton class");
    }
    return rb_mod_autoload(klass, sym, file);
}

          
        

Registers filename to be loaded (using Kernel::require) the first time that module (which may be a String or a symbol) is accessed.

autoload(:MyModule, "/usr/local/lib/modules/my_module.rb")

          
            
static VALUE
rb_f_autoload_p(VALUE obj, VALUE sym)
{
    /* use rb_vm_cbase() as same as rb_f_autoload. */
    VALUE klass = rb_vm_cbase();
    if (NIL_P(klass)) {
        return Qnil;
    }
    return rb_mod_autoload_p(klass, sym);
}

          
        

Returns filename to be loaded if name is registered as autoload.

autoload(:B, "b")
autoload?(:B)            #=> "b"

          
            
static VALUE
rb_f_binding(VALUE self)
{
    return rb_binding_new();
}

          
        

Returns a Binding object, describing the variable and method bindings at the point of call. This object can be used when calling eval to execute the evaluated command in this environment. See also the description of class Binding.

def get_binding(param)
  binding
end
b = get_binding("hello")
eval("param", b)   #=> "hello"

          
            
static VALUE
rb_callcc(VALUE self)
{
    volatile int called;
    volatile VALUE val = cont_capture(&called);

    if (called) {
        return val;
    }
    else {
        return rb_yield(val);
    }
}

          
        

Generates a Continuation object, which it passes to the associated block. You need to require 'continuation' before using this method. Performing a cont.call will cause the callcc to return (as will falling through the end of the block). The value returned by the callcc is the value of the block, or the value passed to cont.call. See class Continuation for more details. Also see Kernel#throw for an alternative mechanism for unwinding a call stack.

          
            
static VALUE
rb_f_caller(int argc, VALUE *argv)
{
    return ec_backtrace_to_ary(GET_EC(), argc, argv, 1, 1, 1);
}

          
        

Returns the current execution stack—an array containing strings in the form file:line or file:line: in `method'.

The optional start parameter determines the number of initial stack entries to omit from the top of the stack.

A second optional length parameter can be used to limit how many entries are returned from the stack.

Returns nil if start is greater than the size of current execution stack.

Optionally you can pass a range, which will return an array containing the entries within the specified range.

def a(skip)
  caller(skip)
end
def b(skip)
  a(skip)
end
def c(skip)
  b(skip)
end
c(0)   #=> ["prog:2:in `a'", "prog:5:in `b'", "prog:8:in `c'", "prog:10:in `<main>'"]
c(1)   #=> ["prog:5:in `b'", "prog:8:in `c'", "prog:11:in `<main>'"]
c(2)   #=> ["prog:8:in `c'", "prog:12:in `<main>'"]
c(3)   #=> ["prog:13:in `<main>'"]
c(4)   #=> []
c(5)   #=> nil

          
            
static VALUE
rb_f_caller_locations(int argc, VALUE *argv)
{
    return ec_backtrace_to_ary(GET_EC(), argc, argv, 1, 1, 0);
}

          
        

Returns the current execution stack—an array containing backtrace location objects.

See Thread::Backtrace::Location for more information.

The optional start parameter determines the number of initial stack entries to omit from the top of the stack.

A second optional length parameter can be used to limit how many entries are returned from the stack.

Returns nil if start is greater than the size of current execution stack.

Optionally you can pass a range, which will return an array containing the entries within the specified range.

          
            
static VALUE
rb_f_catch(int argc, VALUE *argv, VALUE self)
{
    VALUE tag = rb_check_arity(argc, 0, 1) ? argv[0] : rb_obj_alloc(rb_cObject);
    return rb_catch_obj(tag, catch_i, 0);
}

          
        

catch executes its block. If throw is not called, the block executes normally, and catch returns the value of the last expression evaluated.

catch(1) { 123 }            # => 123

If throw(tag2, val) is called, Ruby searches up its stack for a catch block whose tag has the same object_id as tag2. When found, the block stops executing and returns val (or nil if no second argument was given to throw).

catch(1) { throw(1, 456) }  # => 456
catch(1) { throw(1) }       # => nil

When tag is passed as the first argument, catch yields it as the parameter of the block.

catch(1) {|x| x + 2 }       # => 3

When no tag is given, catch yields a new unique object (as from Object.new) as the block parameter. This object can then be used as the argument to throw, and will match the correct catch block.

catch do |obj_A|
  catch do |obj_B|
    throw(obj_B, 123)
    puts "This puts is not reached"
  end

  puts "This puts is displayed"
  456
end

# => 456

catch do |obj_A|
  catch do |obj_B|
    throw(obj_A, 123)
    puts "This puts is still not reached"
  end

  puts "Now this puts is also not reached"
  456
end

# => 123

          
            
static VALUE
rb_f_chomp(int argc, VALUE *argv)
{
    VALUE str = rb_funcall_passing_block(uscore_get(), rb_intern("chomp"), argc, argv);
    rb_lastline_set(str);
    return str;
}

          
        

Equivalent to $_ = $_.chomp(string). See String#chomp. Available only when -p/-n command line option specified.

          
            
static VALUE
rb_f_chop(void)
{
    VALUE str = rb_funcall_passing_block(uscore_get(), rb_intern("chop"), 0, 0);
    rb_lastline_set(str);
    return str;
}

          
        

Equivalent to ($_.dup).chop!, except nil is never returned. See String#chop!. Available only when -p/-n command line option specified.

          
            
VALUE
rb_f_eval(int argc, const VALUE *argv, VALUE self)
{
    VALUE src, scope, vfile, vline;
    VALUE file = Qundef;
    int line = 1;

    rb_scan_args(argc, argv, "13", &src, &scope, &vfile, &vline);
    SafeStringValue(src);
    if (argc >= 3) {
        StringValue(vfile);
    }
    if (argc >= 4) {
        line = NUM2INT(vline);
    }

    if (!NIL_P(vfile))
        file = vfile;

    if (NIL_P(scope))
        return eval_string_with_cref(self, src, NULL, file, line);
    else
        return eval_string_with_scope(scope, src, file, line);
}

          
        

Evaluates the Ruby expression(s) in string. If binding is given, which must be a Binding object, the evaluation is performed in its context. If the optional filename and lineno parameters are present, they will be used when reporting syntax errors.

def get_binding(str)
  return binding
end
str = "hello"
eval "str + ' Fred'"                      #=> "hello Fred"
eval "str + ' Fred'", get_binding("bye")  #=> "bye Fred"

          
            
VALUE
rb_f_exec(int argc, const VALUE *argv)
{
    VALUE execarg_obj, fail_str;
    struct rb_execarg *eargp;
#define CHILD_ERRMSG_BUFLEN 80
    char errmsg[CHILD_ERRMSG_BUFLEN] = { '\0' };
    int err, state;

    execarg_obj = rb_execarg_new(argc, argv, TRUE, FALSE);
    eargp = rb_execarg_get(execarg_obj);
    if (mjit_enabled) mjit_finish(FALSE); /* avoid leaking resources, and do not leave files. XXX: JIT-ed handle can leak after exec error is rescued. */
    before_exec(); /* stop timer thread before redirects */

    rb_protect(rb_execarg_parent_start1, execarg_obj, &state);
    if (state) {
        execarg_parent_end(execarg_obj);
        after_exec(); /* restart timer thread */
        rb_jump_tag(state);
    }

    fail_str = eargp->use_shell ? eargp->invoke.sh.shell_script : eargp->invoke.cmd.command_name;

    err = exec_async_signal_safe(eargp, errmsg, sizeof(errmsg));
    after_exec(); /* restart timer thread */

    rb_exec_fail(eargp, err, errmsg);
    RB_GC_GUARD(execarg_obj);
    rb_syserr_fail_str(err, fail_str);
    UNREACHABLE_RETURN(Qnil);
}

          
        

Replaces the current process by running the given external command, which can take one of the following forms:

exec(commandline)

command line string which is passed to the standard shell

exec(cmdname, arg1, ...)

command name and one or more arguments (no shell)

exec([cmdname, argv0], arg1, ...)

command name, argv and zero or more arguments (no shell)

In the first form, the string is taken as a command line that is subject to shell expansion before being executed.

The standard shell always means "/bin/sh" on Unix-like systems, same as ENV["RUBYSHELL"] (or ENV["COMSPEC"] on Windows NT series), and similar.

If the string from the first form (exec("command")) follows these simple rules:

• no meta characters

• no shell reserved word and no special built-in

• Ruby invokes the command directly without shell

You can force shell invocation by adding “;” to the string (because “;” is a meta character).

Note that this behavior is observable by pid obtained (return value of spawn() and IO#pid for IO.popen) is the pid of the invoked command, not shell.

In the second form (exec("command1", "arg1", ...)), the first is taken as a command name and the rest are passed as parameters to command with no shell expansion.

In the third form (exec(["command", "argv0"], "arg1", ...)), starting a two-element array at the beginning of the command, the first element is the command to be executed, and the second argument is used as the argv[0] value, which may show up in process listings.

In order to execute the command, one of the exec(2) system calls are used, so the running command may inherit some of the environment of the original program (including open file descriptors).

This behavior is modified by the given env and options parameters. See ::spawn for details.

If the command fails to execute (typically Errno::ENOENT when it was not found) a SystemCallError exception is raised.

This method modifies process attributes according to given options before exec(2) system call. See ::spawn for more details about the given options.

The modified attributes may be retained when exec(2) system call fails.

For example, hard resource limits are not restorable.

Consider to create a child process using ::spawn or Kernel#system if this is not acceptable.

exec "echo *"       # echoes list of files in current directory
# never get here

exec "echo", "*"    # echoes an asterisk
# never get here

          
            
VALUE
rb_f_exit(int argc, const VALUE *argv)
{
    int istatus;

    if (rb_check_arity(argc, 0, 1) == 1) {
        istatus = exit_status_code(argv[0]);
    }
    else {
        istatus = EXIT_SUCCESS;
    }
    rb_exit(istatus);

    UNREACHABLE_RETURN(Qnil);
}

          
        

Initiates the termination of the Ruby script by raising the SystemExit exception. This exception may be caught. The optional parameter is used to return a status code to the invoking environment. true and FALSE of status means success and failure respectively. The interpretation of other integer values are system dependent.

begin
  exit
  puts "never get here"
rescue SystemExit
  puts "rescued a SystemExit exception"
end
puts "after begin block"

produces:

rescued a SystemExit exception
after begin block

Just prior to termination, Ruby executes any at_exit functions (see Kernel::at_exit) and runs any object finalizers (see ObjectSpace::define_finalizer).

at_exit { puts "at_exit function" }
ObjectSpace.define_finalizer("string",  proc { puts "in finalizer" })
exit

produces:

at_exit function
in finalizer

          
            
static VALUE
rb_f_exit_bang(int argc, VALUE *argv, VALUE obj)
{
    int istatus;

    if (rb_check_arity(argc, 0, 1) == 1) {
        istatus = exit_status_code(argv[0]);
    }
    else {
        istatus = EXIT_FAILURE;
    }
    _exit(istatus);

    UNREACHABLE_RETURN(Qnil);
}

          
        

Exits the process immediately. No exit handlers are run. status is returned to the underlying system as the exit status.

Process.exit!(true)

          
            
static VALUE
rb_f_fork(VALUE obj)
{
    rb_pid_t pid;

    switch (pid = rb_fork_ruby(NULL)) {
      case 0:
        rb_thread_atfork();
        if (rb_block_given_p()) {
            int status;
            rb_protect(rb_yield, Qundef, &status);
            ruby_stop(status);
        }
        return Qnil;

      case -1:
        rb_sys_fail("fork(2)");
        return Qnil;

      default:
        return PIDT2NUM(pid);
    }
}

          
        

Creates a subprocess. If a block is specified, that block is run in the subprocess, and the subprocess terminates with a status of zero. Otherwise, the fork call returns twice, once in the parent, returning the process ID of the child, and once in the child, returning nil. The child process can exit using Kernel.exit! to avoid running any at_exit functions. The parent process should use Process.wait to collect the termination statuses of its children or use Process.detach to register disinterest in their status; otherwise, the operating system may accumulate zombie processes.

The thread calling fork is the only thread in the created child process. fork doesn’t copy other threads.

If fork is not usable, Process.respond_to?(:fork) returns false.

Note that fork(2) is not available on some platforms like Windows and NetBSD 4. Therefore you should use spawn() instead of fork().

          
            
# File tmp/rubies/ruby-2.6.10/lib/rubygems/core_ext/kernel_gem.rb, line 44
def gem(gem_name, *requirements) # :doc:
  skip_list = (ENV['GEM_SKIP'] || "").split(/:/)
  raise Gem::LoadError, "skipping #{gem_name}" if skip_list.include? gem_name

  if gem_name.kind_of? Gem::Dependency
    unless Gem::Deprecate.skip
      warn "#{Gem.location_of_caller.join ':'}:Warning: Kernel.gem no longer "\
        "accepts a Gem::Dependency object, please pass the name "\
        "and requirements directly"
    end

    requirements = gem_name.requirement
    gem_name = gem_name.name
  end

  dep = Gem::Dependency.new(gem_name, *requirements)

  loaded = Gem.loaded_specs[gem_name]

  return false if loaded && dep.matches_spec?(loaded)

  spec = dep.to_spec

  Gem::LOADED_SPECS_MUTEX.synchronize {
    spec.activate
  } if spec
end

          
        

Use Kernel#gem to activate a specific version of gem_name.

requirements is a list of version requirements that the specified gem must match, most commonly “= example.version.number”. See Gem::Requirement for how to specify a version requirement.

If you will be activating the latest version of a gem, there is no need to call Kernel#gem, Kernel#require will do the right thing for you.

Kernel#gem returns true if the gem was activated, otherwise false. If the gem could not be found, didn’t match the version requirements, or a different version was already activated, an exception will be raised.

Kernel#gem should be called before any require statements (otherwise RubyGems may load a conflicting library version).

Kernel#gem only loads prerelease versions when prerelease requirements are given:

gem 'rake', '>= 1.1.a', '< 2'

In older RubyGems versions, the environment variable GEM_SKIP could be used to skip activation of specified gems, for example to test out changes that haven’t been installed yet. Now RubyGems defers to -I and the RUBYLIB environment variable to skip activation of a gem.

Example:

GEM_SKIP=libA:libB ruby -I../libA -I../libB ./mycode.rb

          
            
static VALUE
rb_f_gets(int argc, VALUE *argv, VALUE recv)
{
    if (recv == argf) {
        return argf_gets(argc, argv, argf);
    }
    return rb_funcallv(argf, idGets, argc, argv);
}

          
        

Returns (and assigns to $_) the next line from the list of files in ARGV (or $*), or from standard input if no files are present on the command line. Returns nil at end of file. The optional argument specifies the record separator. The separator is included with the contents of each record. A separator of nil reads the entire contents, and a zero-length separator reads the input one paragraph at a time, where paragraphs are divided by two consecutive newlines. If the first argument is an integer, or optional second argument is given, the returning string would not be longer than the given value in bytes. If multiple filenames are present in ARGV, gets(nil) will read the contents one file at a time.

ARGV << "testfile"
print while gets

produces:

This is line one
This is line two
This is line three
And so on...

The style of programming using $_ as an implicit parameter is gradually losing favor in the Ruby community.

          
            
VALUE
rb_f_global_variables(void)
{
    VALUE ary = rb_ary_new();
    VALUE sym, backref = rb_backref_get();

    rb_id_table_foreach(rb_global_tbl, gvar_i, (void *)ary);
    if (!NIL_P(backref)) {
	char buf[2];
	int i, nmatch = rb_match_count(backref);
	buf[0] = '$';
	for (i = 1; i <= nmatch; ++i) {
	    if (!rb_match_nth_defined(i, backref)) continue;
	    if (i < 10) {
		/* probably reused, make static ID */
		buf[1] = (char)(i + '0');
		sym = ID2SYM(rb_intern2(buf, 2));
	    }
	    else {
		/* dynamic symbol */
		sym = rb_str_intern(rb_sprintf("$%d", i));
	    }
	    rb_ary_push(ary, sym);
	}
    }
    return ary;
}

          
        

Returns an array of the names of global variables.

global_variables.grep /std/   #=> [:$stdin, :$stdout, :$stderr]

          
            
static VALUE
rb_f_gsub(int argc, VALUE *argv)
{
    VALUE str = rb_funcall_passing_block(uscore_get(), rb_intern("gsub"), argc, argv);
    rb_lastline_set(str);
    return str;
}

          
        

Equivalent to $_.gsub..., except that $_ will be updated if substitution occurs. Available only when -p/-n command line option specified.

          
            
static VALUE
rb_f_block_given_p(void)
{
    rb_execution_context_t *ec = GET_EC();
    rb_control_frame_t *cfp = ec->cfp;
    cfp = vm_get_ruby_level_caller_cfp(ec, RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp));

    if (cfp != NULL && VM_CF_BLOCK_HANDLER(cfp) != VM_BLOCK_HANDLER_NONE) {
        return Qtrue;
    }
    else {
        return Qfalse;
    }
}

          
        

Returns true if yield would execute a block in the current context. The iterator? form is mildly deprecated.

def try
  if block_given?
    yield
  else
    "no block"
  end
end
try                  #=> "no block"
try { "hello" }      #=> "hello"
try do "hello" end   #=> "hello"

          
            
# File tmp/rubies/ruby-2.6.10/ext/json/lib/json/common.rb, line 416
def j(*objs)
  objs.each do |obj|
    puts JSON::generate(obj, :allow_nan => true, :max_nesting => false)
  end
  nil
end

          
        

Outputs objs to STDOUT as JSON strings in the shortest form, that is in one line.

          
            
# File tmp/rubies/ruby-2.6.10/ext/json/lib/json/common.rb, line 425
def jj(*objs)
  objs.each do |obj|
    puts JSON::pretty_generate(obj, :allow_nan => true, :max_nesting => false)
  end
  nil
end

          
        

Outputs objs to STDOUT as JSON strings in a pretty format, with indentation and over many lines.

          
            
VALUE
rb_block_lambda(void)
{
    return proc_new(rb_cProc, TRUE);
}

          
        

Equivalent to Proc.new, except the resulting Proc objects check the number of parameters passed when called.

          
            
static VALUE
rb_f_load(int argc, VALUE *argv)
{
    VALUE fname, wrap, path, orig_fname;

    rb_scan_args(argc, argv, "11", &fname, &wrap);

    orig_fname = rb_get_path_check_to_string(fname, rb_safe_level());
    fname = rb_str_encode_ospath(orig_fname);
    RUBY_DTRACE_HOOK(LOAD_ENTRY, RSTRING_PTR(orig_fname));

    path = rb_find_file(fname);
    if (!path) {
        if (!rb_file_load_ok(RSTRING_PTR(fname)))
            load_failed(orig_fname);
        path = fname;
    }
    rb_load_internal(path, RTEST(wrap));

    RUBY_DTRACE_HOOK(LOAD_RETURN, RSTRING_PTR(orig_fname));

    return Qtrue;
}

          
        

Loads and executes the Ruby program in the file filename. If the filename does not resolve to an absolute path, the file is searched for in the library directories listed in $:. If the optional wrap parameter is true, the loaded script will be executed under an anonymous module, protecting the calling program’s global namespace. In no circumstance will any local variables in the loaded file be propagated to the loading environment.

          
            
static VALUE
rb_f_local_variables(void)
{
    struct local_var_list vars;
    rb_execution_context_t *ec = GET_EC();
    rb_control_frame_t *cfp = vm_get_ruby_level_caller_cfp(ec, RUBY_VM_PREVIOUS_CONTROL_FRAME(ec->cfp));
    unsigned int i;

    local_var_list_init(&vars);
    while (cfp) {
        if (cfp->iseq) {
            for (i = 0; i < cfp->iseq->body->local_table_size; i++) {
                local_var_list_add(&vars, cfp->iseq->body->local_table[i]);
            }
        }
        if (!VM_ENV_LOCAL_P(cfp->ep)) {
            /* block */
            const VALUE *ep = VM_CF_PREV_EP(cfp);

            if (vm_collect_local_variables_in_heap(ep, &vars)) {
                break;
            }
            else {
                while (cfp->ep != ep) {
                    cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
                }
            }
        }
        else {
            break;
        }
    }
    return local_var_list_finish(&vars);
}

          
        

Returns the names of the current local variables.

fred = 1
for i in 1..10
   # ...
end
local_variables   #=> [:fred, :i]

          
            
static VALUE
rb_f_loop(VALUE self)
{
    RETURN_SIZED_ENUMERATOR(self, 0, 0, rb_f_loop_size);
    return rb_rescue2(loop_i, (VALUE)0, loop_stop, (VALUE)0, rb_eStopIteration, (VALUE)0);
}

          
        

Repeatedly executes the block.

If no block is given, an enumerator is returned instead.

loop do
  print "Input: "
  line = gets
  break if !line or line =~ /^qQ/
  # ...
end

StopIteration raised in the block breaks the loop. In this case, loop returns the “result” value stored in the exception.

enum = Enumerator.new { |y|
  y << "one"
  y << "two"
  :ok
}

result = loop {
  puts enum.next
} #=> :ok

          
            
static VALUE
rb_f_open(int argc, VALUE *argv)
{
    ID to_open = 0;
    int redirect = FALSE;

    if (argc >= 1) {
        CONST_ID(to_open, "to_open");
        if (rb_respond_to(argv[0], to_open)) {
            redirect = TRUE;
        }
        else {
            VALUE tmp = argv[0];
            FilePathValue(tmp);
            if (NIL_P(tmp)) {
                redirect = TRUE;
            }
            else {
                VALUE cmd = check_pipe_command(tmp);
                if (!NIL_P(cmd)) {
                    argv[0] = cmd;
                    return rb_io_s_popen(argc, argv, rb_cIO);
                }
            }
        }
    }
    if (redirect) {
        VALUE io = rb_funcallv(argv[0], to_open, argc-1, argv+1);

        if (rb_block_given_p()) {
            return rb_ensure(rb_yield, io, io_close, io);
        }
        return io;
    }
    return rb_io_s_open(argc, argv, rb_cFile);
}

          
        

Creates an IO object connected to the given stream, file, or subprocess.

If path does not start with a pipe character (|), treat it as the name of a file to open using the specified mode (defaulting to “r”).

The mode is either a string or an integer. If it is an integer, it must be bitwise-or of open(2) flags, such as File::RDWR or File::EXCL. If it is a string, it is either “fmode”, “fmode:ext_enc”, or “fmode:ext_enc:int_enc”.

See the documentation of IO.new for full documentation of the mode string directives.

If a file is being created, its initial permissions may be set using the perm parameter. See File.new and the open(2) and chmod(2) man pages for a description of permissions.

If a block is specified, it will be invoked with the IO object as a parameter, and the IO will be automatically closed when the block terminates. The call returns the value of the block.

If path starts with a pipe character ("|"), a subprocess is created, connected to the caller by a pair of pipes. The returned IO object may be used to write to the standard input and read from the standard output of this subprocess.

If the command following the pipe is a single minus sign ("|-"), Ruby forks, and this subprocess is connected to the parent. If the command is not "-", the subprocess runs the command.

When the subprocess is Ruby (opened via "|-"), the open call returns nil. If a block is associated with the open call, that block will run twice — once in the parent and once in the child.

The block parameter will be an IO object in the parent and nil in the child. The parent’s IO object will be connected to the child’s $stdin and $stdout. The subprocess will be terminated at the end of the block.

Examples

Reading from “testfile”:

open("testfile") do |f|
  print f.gets
end

Produces:

This is line one

Open a subprocess and read its output:

cmd = open("|date")
print cmd.gets
cmd.close

Produces:

Wed Apr  9 08:56:31 CDT 2003

Open a subprocess running the same Ruby program:

f = open("|-", "w+")
if f.nil?
  puts "in Child"
  exit
else
  puts "Got: #{f.gets}"
end

Produces:

Got: in Child

Open a subprocess using a block to receive the IO object:

open "|-" do |f|
  if f then
    # parent process
    puts "Got: #{f.gets}"
  else
    # child process
    puts "in Child"
  end
end

Produces:

Got: in Child

          
            
static VALUE
rb_f_p(int argc, VALUE *argv, VALUE self)
{
    struct rb_f_p_arg arg;
    arg.argc = argc;
    arg.argv = argv;

    return rb_uninterruptible(rb_f_p_internal, (VALUE)&arg);
}

          
        

For each object, directly writes obj.inspect followed by a newline to the program’s standard output.

S = Struct.new(:name, :state)
s = S['dave', 'TX']
p s

produces:

#<S name="dave", state="TX">

          
            
# File tmp/rubies/ruby-2.6.10/lib/pp.rb, line 582
def pp(*objs)
  objs.each {|obj|
    PP.pp(obj)
  }
  objs.size <= 1 ? objs.first : objs
end

          
        

prints arguments in pretty form.

pp returns argument(s).

          
            
# File tmp/rubies/ruby-2.6.10/lib/pp.rb, line 575
def pretty_inspect
  PP.pp(self, ''.dup)
end

          
        

Returns a pretty printed object as a string.

In order to use this method you must first require the PP module:

require 'pp'

See the PP module for more information.

          
            
static VALUE
rb_f_print(int argc, const VALUE *argv)
{
    rb_io_print(argc, argv, rb_stdout);
    return Qnil;
}

          
        

Prints each object in turn to $stdout. If the output field separator ($,) is not nil, its contents will appear between each field. If the output record separator ($\) is not nil, it will be appended to the output. If no arguments are given, prints $_. Objects that aren’t strings will be converted by calling their to_s method.

print "cat", [1,2,3], 99, "\n"
$, = ", "
$\ = "\n"
print "cat", [1,2,3], 99

produces:

cat12399
cat, 1, 2, 3, 99

          
            
static VALUE
rb_f_printf(int argc, VALUE *argv)
{
    VALUE out;

    if (argc == 0) return Qnil;
    if (RB_TYPE_P(argv[0], T_STRING)) {
        out = rb_stdout;
    }
    else {
        out = argv[0];
        argv++;
        argc--;
    }
    rb_io_write(out, rb_f_sprintf(argc, argv));

    return Qnil;
}

          
        

Equivalent to:

io.write(sprintf(string, obj, ...))

or

$stdout.write(sprintf(string, obj, ...))

          
            
VALUE
rb_block_proc(void)
{
    return proc_new(rb_cProc, FALSE);
}

          
        

Equivalent to Proc.new.

          
            
static VALUE
rb_f_putc(VALUE recv, VALUE ch)
{
    if (recv == rb_stdout) {
        return rb_io_putc(recv, ch);
    }
    return rb_funcallv(rb_stdout, rb_intern("putc"), 1, &ch);
}

          
        

Equivalent to:

$stdout.putc(int)

Refer to the documentation for IO#putc for important information regarding multi-byte characters.

          
            
static VALUE
rb_f_puts(int argc, VALUE *argv, VALUE recv)
{
    if (recv == rb_stdout) {
        return rb_io_puts(argc, argv, recv);
    }
    return rb_funcallv(rb_stdout, rb_intern("puts"), argc, argv);
}

          
        

Equivalent to

$stdout.puts(obj, ...)

          
            
static VALUE
rb_f_raise(int argc, VALUE *argv)
{
    VALUE err;
    VALUE opts[raise_max_opt], *const cause = &opts[raise_opt_cause];

    argc = extract_raise_opts(argc, argv, opts);
    if (argc == 0) {
        if (*cause != Qundef) {
            rb_raise(rb_eArgError, "only cause is given with no arguments");
        }
        err = get_errinfo();
        if (!NIL_P(err)) {
            argc = 1;
            argv = &err;
        }
    }
    rb_raise_jump(rb_make_exception(argc, argv), *cause);

    UNREACHABLE_RETURN(Qnil);
}

          
        

With no arguments, raises the exception in $! or raises a RuntimeError if $! is nil. With a single String argument, raises a RuntimeError with the string as a message. Otherwise, the first parameter should be the name of an Exception class (or an object that returns an Exception object when sent an exception message). The optional second parameter sets the message associated with the exception, and the third parameter is an array of callback information. Exceptions are caught by the rescue clause of begin...end blocks.

raise "Failed to create socket"
raise ArgumentError, "No parameters", caller

The cause of the generated exception is automatically set to the “current” exception ($!) if any. An alternative value, either an Exception object or nil, can be specified via the :cause argument.

          
            
static VALUE
rb_f_rand(int argc, VALUE *argv, VALUE obj)
{
    VALUE vmax;
    rb_random_t *rnd = rand_start(&default_rand);

    if (rb_check_arity(argc, 0, 1) && !NIL_P(vmax = argv[0])) {
        VALUE v = rand_range(Qnil, rnd, vmax);
        if (v != Qfalse) return v;
        vmax = rb_to_int(vmax);
        if (vmax != INT2FIX(0)) {
            v = rand_int(Qnil, rnd, vmax, 0);
            if (!NIL_P(v)) return v;
        }
    }
    return DBL2NUM(genrand_real(&rnd->mt));
}

          
        

If called without an argument, or if max.to_i.abs == 0, rand returns a pseudo-random floating point number between 0.0 and 1.0, including 0.0 and excluding 1.0.

rand        #=> 0.2725926052826416

When max.abs is greater than or equal to 1, rand returns a pseudo-random integer greater than or equal to 0 and less than max.to_i.abs.

rand(100)   #=> 12

When max is a Range, rand returns a random number where range.member?(number) == true.

Negative or floating point values for max are allowed, but may give surprising results.

rand(-100) # => 87
rand(-0.5) # => 0.8130921818028143
rand(1.9)  # equivalent to rand(1), which is always 0

Kernel.srand may be used to ensure that sequences of random numbers are reproducible between different runs of a program.

See also Random.rand.

          
            
static VALUE
rb_f_readline(int argc, VALUE *argv, VALUE recv)
{
    if (recv == argf) {
        return argf_readline(argc, argv, argf);
    }
    return rb_funcallv(argf, rb_intern("readline"), argc, argv);
}

          
        

Equivalent to Kernel::gets, except readline raises EOFError at end of file.

          
            
static VALUE
rb_f_readlines(int argc, VALUE *argv, VALUE recv)
{
    if (recv == argf) {
        return argf_readlines(argc, argv, argf);
    }
    return rb_funcallv(argf, rb_intern("readlines"), argc, argv);
}

          
        

Returns an array containing the lines returned by calling Kernel.gets(sep) until the end of file.

          
            
# File tmp/rubies/ruby-2.6.10/lib/rubygems/core_ext/kernel_require.rb, line 34
def require(path)
  RUBYGEMS_ACTIVATION_MONITOR.enter

  path = path.to_path if path.respond_to? :to_path

  if spec = Gem.find_unresolved_default_spec(path)
    Gem.remove_unresolved_default_spec(spec)
    begin
      Kernel.send(:gem, spec.name)
    rescue Exception
      RUBYGEMS_ACTIVATION_MONITOR.exit
      raise
    end
  end

  # If there are no unresolved deps, then we can use just try
  # normal require handle loading a gem from the rescue below.

  if Gem::Specification.unresolved_deps.empty?
    RUBYGEMS_ACTIVATION_MONITOR.exit
    return gem_original_require(path)
  end

  # If +path+ is for a gem that has already been loaded, don't
  # bother trying to find it in an unresolved gem, just go straight
  # to normal require.
  #--
  # TODO request access to the C implementation of this to speed up RubyGems

  if Gem::Specification.find_active_stub_by_path(path)
    RUBYGEMS_ACTIVATION_MONITOR.exit
    return gem_original_require(path)
  end

  # Attempt to find +path+ in any unresolved gems...

  found_specs = Gem::Specification.find_in_unresolved path

  # If there are no directly unresolved gems, then try and find +path+
  # in any gems that are available via the currently unresolved gems.
  # For example, given:
  #
  #   a => b => c => d
  #
  # If a and b are currently active with c being unresolved and d.rb is
  # requested, then find_in_unresolved_tree will find d.rb in d because
  # it's a dependency of c.
  #
  if found_specs.empty?
    found_specs = Gem::Specification.find_in_unresolved_tree path

    found_specs.each do |found_spec|
      found_spec.activate
    end

  # We found +path+ directly in an unresolved gem. Now we figure out, of
  # the possible found specs, which one we should activate.
  else

    # Check that all the found specs are just different
    # versions of the same gem
    names = found_specs.map(&:name).uniq

    if names.size > 1
      RUBYGEMS_ACTIVATION_MONITOR.exit
      raise Gem::LoadError, "#{path} found in multiple gems: #{names.join ', '}"
    end

    # Ok, now find a gem that has no conflicts, starting
    # at the highest version.
    valid = found_specs.find { |s| !s.has_conflicts? }

    unless valid
      le = Gem::LoadError.new "unable to find a version of '#{names.first}' to activate"
      le.name = names.first
      RUBYGEMS_ACTIVATION_MONITOR.exit
      raise le
    end

    valid.activate
  end

  RUBYGEMS_ACTIVATION_MONITOR.exit
  return gem_original_require(path)
rescue LoadError => load_error
  RUBYGEMS_ACTIVATION_MONITOR.enter

  begin
    if load_error.message.start_with?("Could not find") or
        (load_error.message.end_with?(path) and Gem.try_activate(path))
      require_again = true
    end
  ensure
    RUBYGEMS_ACTIVATION_MONITOR.exit
  end

  return gem_original_require(path) if require_again

  raise load_error
end

          
        

When RubyGems is required, Kernel#require is replaced with our own which is capable of loading gems on demand.

When you call require 'x', this is what happens:

• If the file can be loaded from the existing Ruby loadpath, it is.

• Otherwise, installed gems are searched for a file that matches. If it’s found in gem ‘y’, that gem is activated (added to the loadpath).

The normal require functionality of returning false if that file has already been loaded is preserved.

          
            
VALUE
rb_f_require_relative(VALUE obj, VALUE fname)
{
    VALUE base = rb_current_realfilepath();
    if (NIL_P(base)) {
        rb_loaderror("cannot infer basepath");
    }
    base = rb_file_dirname(base);
    return rb_require_safe(rb_file_absolute_path(fname, base), rb_safe_level());
}

          
        

Ruby tries to load the library named string relative to the requiring file’s path. If the file’s path cannot be determined a LoadError is raised. If a file is loaded true is returned and false otherwise.

          
            
# File tmp/rubies/ruby-2.6.10/lib/scanf.rb, line 773
def scanf(format, &b) #:doc:
  STDIN.scanf(format ,&b)
end

          
        

Scans STDIN for data matching format. See IO#scanf for details.

See Scanf for details on creating a format string.

You will need to require ‘scanf’ to use Kernel#scanf.

          
            
static VALUE
rb_f_select(int argc, VALUE *argv, VALUE obj)
{
    VALUE timeout;
    struct select_args args;
    struct timeval timerec;
    int i;

    rb_scan_args(argc, argv, "13", &args.read, &args.write, &args.except, &timeout);
    if (NIL_P(timeout)) {
        args.timeout = 0;
    }
    else {
        timerec = rb_time_interval(timeout);
        args.timeout = &timerec;
    }

    for (i = 0; i < numberof(args.fdsets); ++i)
        rb_fd_init(&args.fdsets[i]);

    return rb_ensure(select_call, (VALUE)&args, select_end, (VALUE)&args);
}

          
        

Calls select(2) system call. It monitors given arrays of IO objects, waits until one or more of IO objects are ready for reading, are ready for writing, and have pending exceptions respectively, and returns an array that contains arrays of those IO objects. It will return nil if optional timeout value is given and no IO object is ready in timeout seconds.

IO.select peeks the buffer of IO objects for testing readability. If the IO buffer is not empty, IO.select immediately notifies readability. This “peek” only happens for IO objects. It does not happen for IO-like objects such as OpenSSL::SSL::SSLSocket.

The best way to use IO.select is invoking it after nonblocking methods such as read_nonblock, write_nonblock, etc. The methods raise an exception which is extended by IO::WaitReadable or IO::WaitWritable. The modules notify how the caller should wait with IO.select. If IO::WaitReadable is raised, the caller should wait for reading. If IO::WaitWritable is raised, the caller should wait for writing.

So, blocking read (readpartial) can be emulated using read_nonblock and IO.select as follows:

begin
  result = io_like.read_nonblock(maxlen)
rescue IO::WaitReadable
  IO.select([io_like])
  retry
rescue IO::WaitWritable
  IO.select(nil, [io_like])
  retry
end

Especially, the combination of nonblocking methods and IO.select is preferred for IO like objects such as OpenSSL::SSL::SSLSocket. It has to_io method to return underlying IO object. IO.select calls to_io to obtain the file descriptor to wait.

This means that readability notified by IO.select doesn’t mean readability from OpenSSL::SSL::SSLSocket object.

The most likely situation is that OpenSSL::SSL::SSLSocket buffers some data. IO.select doesn’t see the buffer. So IO.select can block when OpenSSL::SSL::SSLSocket#readpartial doesn’t block.

However, several more complicated situations exist.

SSL is a protocol which is sequence of records. The record consists of multiple bytes. So, the remote side of SSL sends a partial record, IO.select notifies readability but OpenSSL::SSL::SSLSocket cannot decrypt a byte and OpenSSL::SSL::SSLSocket#readpartial will block.

Also, the remote side can request SSL renegotiation which forces the local SSL engine to write some data. This means OpenSSL::SSL::SSLSocket#readpartial may invoke write system call and it can block. In such a situation, OpenSSL::SSL::SSLSocket#read_nonblock raises IO::WaitWritable instead of blocking. So, the caller should wait for ready for writability as above example.

The combination of nonblocking methods and IO.select is also useful for streams such as tty, pipe socket socket when multiple processes read from a stream.

Finally, Linux kernel developers don’t guarantee that readability of select(2) means readability of following read(2) even for a single process. See select(2) manual on GNU/Linux system.

Invoking IO.select before IO#readpartial works well as usual. However it is not the best way to use IO.select.

The writability notified by select(2) doesn’t show how many bytes are writable. IO#write method blocks until given whole string is written. So, IO#write(two or more bytes) can block after writability is notified by IO.select. IO#write_nonblock is required to avoid the blocking.

Blocking write (write) can be emulated using write_nonblock and IO.select as follows: IO::WaitReadable should also be rescued for SSL renegotiation in OpenSSL::SSL::SSLSocket.

while 0 < string.bytesize
  begin
    written = io_like.write_nonblock(string)
  rescue IO::WaitReadable
    IO.select([io_like])
    retry
  rescue IO::WaitWritable
    IO.select(nil, [io_like])
    retry
  end
  string = string.byteslice(written..-1)
end

Parameters

read_array

an array of IO objects that wait until ready for read

write_array

an array of IO objects that wait until ready for write

error_array

an array of IO objects that wait for exceptions

timeout

a numeric value in second

Example

rp, wp = IO.pipe
mesg = "ping "
100.times {
  # IO.select follows IO#read.  Not the best way to use IO.select.
  rs, ws, = IO.select([rp], [wp])
  if r = rs[0]
    ret = r.read(5)
    print ret
    case ret
    when /ping/
      mesg = "pong\n"
    when /pong/
      mesg = "ping "
    end
  end
  if w = ws[0]
    w.write(mesg)
  end
}

produces:

ping pong
ping pong
ping pong
(snipped)
ping