Removes the definition of the given constant, returning that constant’s previous value. If that constant referred to a module, this will not change that module’s name and can lead to confusion.
Removes the last List
.
Removes server
from the list of registered servers.
Removes server
from the list of registered servers.
Removes the method identified by symbol from the current class. For an example, see Module#undef_method
. String
arguments are converted to symbols.
Removes the entry given by path
, which should be the entry for a regular file, a symbolic link, or a directory.
Argument path
should be interpretable as a path.
Optional argument force
specifies whether to ignore raised exceptions of StandardError
and its descendants.
Related: FileUtils.remove_entry_secure
.
Removes the entry given by path
, which should be the entry for a regular file, a symbolic link, or a directory.
Argument path
should be interpretable as a path.
Optional argument force
specifies whether to ignore raised exceptions of StandardError
and its descendants.
Related: FileUtils.remove_entry_secure
.
Removes the file entry given by path
, which should be the entry for a regular file or a symbolic link.
Argument path
should be interpretable as a path.
Optional argument force
specifies whether to ignore raised exceptions of StandardError
and its descendants.
Related: methods for deleting.
Removes the file entry given by path
, which should be the entry for a regular file or a symbolic link.
Argument path
should be interpretable as a path.
Optional argument force
specifies whether to ignore raised exceptions of StandardError
and its descendants.
Related: methods for deleting.
Recursively removes the directory entry given by path
, which should be the entry for a regular file, a symbolic link, or a directory.
Argument path
should be interpretable as a path.
Optional argument force
specifies whether to ignore raised exceptions of StandardError
and its descendants.
Related: methods for deleting.
Recursively removes the directory entry given by path
, which should be the entry for a regular file, a symbolic link, or a directory.
Argument path
should be interpretable as a path.
Optional argument force
specifies whether to ignore raised exceptions of StandardError
and its descendants.
Related: methods for deleting.
the spec of the gem to be uninstalled
Returns whether or not the constant const
is defined. You may optionally pass the type
of const
as [const, type]
, such as:
have_const(%w[PTHREAD_MUTEX_INITIALIZER pthread_mutex_t], "pthread.h")
You may also pass additional headers
to check against in addition to the common header files, and additional flags to opt
which are then passed along to the compiler.
If found, a macro is passed as a preprocessor constant to the compiler using the type name, in uppercase, prepended with HAVE_CONST_
.
For example, if have_const('foo')
returned true, then the HAVE_CONST_FOO
preprocessor macro would be passed to the compiler.
Removes the named instance variable from obj, returning that variable’s value. String
arguments are converted to symbols.
class Dummy attr_reader :var def initialize @var = 99 end def remove remove_instance_variable(:@var) end end d = Dummy.new d.var #=> 99 d.remove #=> 99 d.var #=> nil
Remove previously defined command-line argument name
.
Invoked as a callback whenever a constant is assigned on the receiver
module Chatty def self.const_added(const_name) super puts "Added #{const_name.inspect}" end FOO = 1 end
produces:
Added :FOO
Checks for a constant with the given name in mod. If inherit
is set, the lookup will also search the ancestors (and Object
if mod is a Module
).
The value of the constant is returned if a definition is found, otherwise a NameError
is raised.
Math.const_get(:PI) #=> 3.14159265358979
This method will recursively look up constant names if a namespaced class name is provided. For example:
module Foo; class Bar; end end Object.const_get 'Foo::Bar'
The inherit
flag is respected on each lookup. For example:
module Foo class Bar VAL = 10 end class Baz < Bar; end end Object.const_get 'Foo::Baz::VAL' # => 10 Object.const_get 'Foo::Baz::VAL', false # => NameError
If the argument is not a valid constant name a NameError
will be raised with a warning “wrong constant name”.
Object.const_get 'foobar' #=> NameError: wrong constant name foobar
Sets the named constant to the given object, returning that object. Creates a new constant if no constant with the given name previously existed.
Math.const_set("HIGH_SCHOOL_PI", 22.0/7.0) #=> 3.14285714285714 Math::HIGH_SCHOOL_PI - Math::PI #=> 0.00126448926734968
If sym
or str
is not a valid constant name a NameError
will be raised with a warning “wrong constant name”.
Object.const_set('foobar', 42) #=> NameError: wrong constant name foobar
Says whether mod or its ancestors have a constant with the given name:
Float.const_defined?(:EPSILON) #=> true, found in Float itself Float.const_defined?("String") #=> true, found in Object (ancestor) BasicObject.const_defined?(:Hash) #=> false
If mod is a Module
, additionally Object
and its ancestors are checked:
Math.const_defined?(:String) #=> true, found in Object
In each of the checked classes or modules, if the constant is not present but there is an autoload for it, true
is returned directly without autoloading:
module Admin autoload :User, 'admin/user' end Admin.const_defined?(:User) #=> true
If the constant is not found the callback const_missing
is not called and the method returns false
.
If inherit
is false, the lookup only checks the constants in the receiver:
IO.const_defined?(:SYNC) #=> true, found in File::Constants (ancestor) IO.const_defined?(:SYNC, false) #=> false, not found in IO itself
In this case, the same logic for autoloading applies.
If the argument is not a valid constant name a NameError
is raised with the message “wrong constant name name”:
Hash.const_defined? 'foobar' #=> NameError: wrong constant name foobar
Invoked when a reference is made to an undefined constant in mod. It is passed a symbol for the undefined constant, and returns a value to be used for that constant. The following code is an example of the same:
def Foo.const_missing(name) name # return the constant name as Symbol end Foo::UNDEFINED_CONST #=> :UNDEFINED_CONST: symbol returned
In the next example when a reference is made to an undefined constant, it attempts to load a file whose name is the lowercase version of the constant (thus class Fred
is assumed to be in file fred.rb
). If found, it returns the loaded class. It therefore implements an autoload feature similar to Kernel#autoload
and Module#autoload
.
def Object.const_missing(name) @looked_for ||= {} str_name = name.to_s raise "Class not found: #{name}" if @looked_for[str_name] @looked_for[str_name] = 1 file = str_name.downcase require file klass = const_get(name) return klass if klass raise "Class not found: #{name}" end
Defines the constants of OLE Automation server as mod’s constants. The first argument is WIN32OLE
object or type library name. If 2nd argument is omitted, the default is WIN32OLE
. The first letter of Ruby’s constant variable name is upper case, so constant variable name of WIN32OLE
object is capitalized. For example, the ‘xlTop’ constant of Excel is changed to ‘XlTop’ in WIN32OLE
. If the first letter of constant variable is not [A-Z], then the constant is defined as CONSTANTS hash element.
module EXCEL_CONST end excel = WIN32OLE.new('Excel.Application') WIN32OLE.const_load(excel, EXCEL_CONST) puts EXCEL_CONST::XlTop # => -4160 puts EXCEL_CONST::CONSTANTS['_xlDialogChartSourceData'] # => 541 WIN32OLE.const_load(excel) puts WIN32OLE::XlTop # => -4160 module MSO end WIN32OLE.const_load('Microsoft Office 9.0 Object Library', MSO) puts MSO::MsoLineSingle # => 1