Evaluates a string containing Ruby source code, or the given block, within the context of the receiver (obj). In order to set the context, the variable self is set to obj while the code is executing, giving the code access to obj’s instance variables and private methods.
When instance_eval is given a block, obj is also passed in as the block’s only argument.
When instance_eval is given a String, the optional second and third parameters supply a filename and starting line number that are used when reporting compilation errors.
class KlassWithSecret def initialize @secret = 99 end private def the_secret "Ssssh! The secret is #{@secret}." end end k = KlassWithSecret.new k.instance_eval { @secret } #=> 99 k.instance_eval { the_secret } #=> "Ssssh! The secret is 99." k.instance_eval {|obj| obj == self } #=> true
Executes the given block within the context of the receiver (obj). In order to set the context, the variable self is set to obj while the code is executing, giving the code access to obj’s instance variables. Arguments are passed as block parameters.
class KlassWithSecret def initialize @secret = 99 end end k = KlassWithSecret.new k.instance_exec(5) {|x| @secret+x } #=> 104
Returns self.
Returns a Proc object that maps a key to its value:
h = {foo: 0, bar: 1, baz: 2} proc = h.to_proc proc.class # => Proc proc.call(:foo) # => 0 proc.call(:bar) # => 1 proc.call(:nosuch) # => nil
Returns a new Hash object; each entry has:
A key provided by the block.
The value from self.
An optional hash argument can be provided to map keys to new keys. Any key not given will be mapped using the provided block, or remain the same if no block is given.
Transform keys:
h = {foo: 0, bar: 1, baz: 2} h1 = h.transform_keys {|key| key.to_s } h1 # => {"foo"=>0, "bar"=>1, "baz"=>2} h.transform_keys(foo: :bar, bar: :foo) #=> {bar: 0, foo: 1, baz: 2} h.transform_keys(foo: :hello, &:to_s) #=> {hello: 0, "bar" => 1, "baz" => 2}
Overwrites values for duplicate keys:
h = {foo: 0, bar: 1, baz: 2} h1 = h.transform_keys {|key| :bat } h1 # => {bat: 2}
Returns a new Enumerator if no block given:
h = {foo: 0, bar: 1, baz: 2} e = h.transform_keys # => #<Enumerator: {foo: 0, bar: 1, baz: 2}:transform_keys> h1 = e.each { |key| key.to_s } h1 # => {"foo"=>0, "bar"=>1, "baz"=>2}
Same as Hash#transform_keys but modifies the receiver in place instead of returning a new hash.
Returns a new Hash object; each entry has:
A key from self.
A value provided by the block.
Transform values:
h = {foo: 0, bar: 1, baz: 2} h1 = h.transform_values {|value| value * 100} h1 # => {foo: 0, bar: 100, baz: 200}
Returns a new Enumerator if no block given:
h = {foo: 0, bar: 1, baz: 2} e = h.transform_values # => #<Enumerator: {foo: 0, bar: 1, baz: 2}:transform_values> h1 = e.each { |value| value * 100} h1 # => {foo: 0, bar: 100, baz: 200}
Returns self, whose keys are unchanged, and whose values are determined by the given block.
h = {foo: 0, bar: 1, baz: 2} h.transform_values! {|value| value * 100} # => {foo: 0, bar: 100, baz: 200}
Returns a new Enumerator if no block given:
h = {foo: 0, bar: 1, baz: 2} e = h.transform_values! # => #<Enumerator: {foo: 0, bar: 100, baz: 200}:transform_values!> h1 = e.each {|value| value * 100} h1 # => {foo: 0, bar: 100, baz: 200}
Returns a Hash containing all name/value pairs from ENV:
ENV.replace('foo' => '0', 'bar' => '1') ENV.to_hash # => {"bar"=>"1", "foo"=>"0"}
Returns an IO object representing the current file. This will be a File object unless the current file is a stream such as STDIN.
For example:
ARGF.to_io #=> #<File:glark.txt> ARGF.to_io #=> #<IO:<STDIN>>
Reads at most maxlen bytes from the ARGF stream in non-blocking mode.
Returns a new binding each time near TOPLEVEL_BINDING for runs that do not specify a binding.
Creates a new ipaddr containing the given network byte ordered string form of an IP address.
Returns a json string containing the IP address representation.
Creates a Range object for the network address.
Returns the usable width for out. As the width of out:
If out is assigned to a tty device, its width is used.
Otherwise, or it could not get the value, the COLUMN environment variable is assumed to be set to the width.
If COLUMN is not set to a non-zero number, 80 is assumed.
And finally, returns the above width value - 1.
This -1 is for Windows command prompt, which moves the cursor to the next line if it reaches the last column.
Returns a hash of the name/value pairs, to use in pattern matching.
Measure = Data.define(:amount, :unit) distance = Measure[10, 'km'] distance.deconstruct_keys(nil) #=> {:amount=>10, :unit=>"km"} distance.deconstruct_keys([:amount]) #=> {:amount=>10} # usage case distance in amount:, unit: 'km' # calls #deconstruct_keys underneath puts "It is #{amount} kilometers away" else puts "Don't know how to handle it" end # prints "It is 10 kilometers away"
Or, with checking the class, too:
case distance in Measure(amount:, unit: 'km') puts "It is #{amount} kilometers away" # ... end
Returns a hash of the named captures; each key is a capture name; each value is its captured string or nil:
m = /(?<foo>.)(.)(?<bar>.+)/.match("hoge") # => #<MatchData "hoge" foo:"h" bar:"ge"> m.named_captures # => {"foo"=>"h", "bar"=>"ge"} m = /(?<a>.)(?<b>.)/.match("01") # => #<MatchData "01" a:"0" b:"1"> m.named_captures #=> {"a" => "0", "b" => "1"} m = /(?<a>.)(?<b>.)?/.match("0") # => #<MatchData "0" a:"0" b:nil> m.named_captures #=> {"a" => "0", "b" => nil} m = /(?<a>.)(?<a>.)/.match("01") # => #<MatchData "01" a:"0" a:"1"> m.named_captures #=> {"a" => "1"}
If keyword argument symbolize_names is given a true value, the keys in the resulting hash are Symbols:
m = /(?<a>.)(?<a>.)/.match("01") # => #<MatchData "01" a:"0" a:"1"> m.named_captures(symbolize_names: true) #=> {:a => "1"}
Returns a hash of the named captures for the given names.
m = /(?<hours>\d{2}):(?<minutes>\d{2}):(?<seconds>\d{2})/.match("18:37:22") m.deconstruct_keys([:hours, :minutes]) # => {:hours => "18", :minutes => "37"} m.deconstruct_keys(nil) # => {:hours => "18", :minutes => "37", :seconds => "22"}
Returns an empty hash if no named captures were defined:
m = /(\d{2}):(\d{2}):(\d{2})/.match("18:37:22") m.deconstruct_keys(nil) # => {}
Returns the substring of the target string from its beginning up to the first match in self (that is, self[0]); equivalent to regexp global variable $`:
m = /(.)(.)(\d+)(\d)/.match("THX1138.") # => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8"> m[0] # => "HX1138" m.pre_match # => "T"
Related: MatchData#post_match.
Returns the substring of the target string from the end of the first match in self (that is, self[0]) to the end of the string; equivalent to regexp global variable $':
m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie") # => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8"> m[0] # => "HX1138" m.post_match # => ": The Movie"\
Related: MatchData.pre_match.
This is similar to PrettyPrint::format but the result has no breaks.
maxwidth, newline and genspace are ignored.
The invocation of breakable in the block doesn’t break a line and is treated as just an invocation of text.
Returns the group most recently added to the stack.
Contrived example:
out = ""
=> ""
q = PrettyPrint.new(out)
=> #<PrettyPrint:0x82f85c0 @output="", @maxwidth=79, @newline="\n", @genspace=#<Proc:0x82f8368@/home/vbatts/.rvm/rubies/ruby-head/lib/ruby/2.0.0/prettyprint.rb:82 (lambda)>, @output_width=0, @buffer_width=0, @buffer=[], @group_stack=[#<PrettyPrint::Group:0x82f8138 @depth=0, @breakables=[], @break=false>], @group_queue=#<PrettyPrint::GroupQueue:0x82fb7c0 @queue=[[#<PrettyPrint::Group:0x82f8138 @depth=0, @breakables=[], @break=false>]]>, @indent=0>
q.group {
q.text q.current_group.inspect
q.text q.newline
q.group(q.current_group.depth + 1) {
q.text q.current_group.inspect
q.text q.newline
q.group(q.current_group.depth + 1) {
q.text q.current_group.inspect
q.text q.newline
q.group(q.current_group.depth + 1) {
q.text q.current_group.inspect
q.text q.newline
}
}
}
}
=> 284
puts out
#<PrettyPrint::Group:0x8354758 @depth=1, @breakables=[], @break=false>
#<PrettyPrint::Group:0x8354550 @depth=2, @breakables=[], @break=false>
#<PrettyPrint::Group:0x83541cc @depth=3, @breakables=[], @break=false>
#<PrettyPrint::Group:0x8347e54 @depth=4, @breakables=[], @break=false>
This is similar to breakable except the decision to break or not is determined individually.
Two fill_breakable under a group may cause 4 results: (break,break), (break,non-break), (non-break,break), (non-break,non-break). This is different to breakable because two breakable under a group may cause 2 results: (break,break), (non-break,non-break).
The text sep is inserted if a line is not broken at this point.
If sep is not specified, “ ” is used.
If width is not specified, sep.length is used. You will have to specify this when sep is a multibyte character, for example.
Iterates over all IP addresses for name.