Class: Proc

Inherits:
NSObject show all

Overview

defined in eval.c for WTF reason

Class Method Summary (collapse)

Instance Method Summary (collapse)

Methods inherited from NSObject

#!, #!=, #!~, #, #=~, #Rational, #__callee__, #__method__, #__send__, #__type__, `, alloc, allocWithZone:, #autoContentAccessingProxy, autoload, autoload?, autorelease_pool, #awakeAfterUsingCoder:, binding, block_given?, caller, cancelPreviousPerformRequestsWithTarget:, cancelPreviousPerformRequestsWithTarget:selector:object:, catch, class, classFallbacksForKeyedArchiver, #classForCoder, #classForKeyedArchiver, classForKeyedUnarchiver, conformsToProtocol:, #copy, copyWithZone:, #dealloc, #define_singleton_method, description, display, #doesNotRecognizeSelector:, #enum_for, #equal?, #extend, fail, #finalize, format, #forwardInvocation:, #forwardingTargetForSelector:, framework, #freeze, #frozen?, getpass, gets, global_variables, #init, initialize, #initialize_clone, #initialize_copy, #initialize_dup, #inspect, instanceMethodForSelector:, instanceMethodSignatureForSelector:, #instance_eval, #instance_exec, #instance_of?, #instance_variable_defined?, #instance_variable_get, #instance_variable_set, #instance_variables, instancesRespondToSelector:, isSubclassOfClass:, #is_a?, iterator?, #kind_of?, lambda, load, load_bridge_support_file, load_plist, local_variables, loop, #method, #methodForSelector:, #methodSignatureForSelector:, #methods, #mutableCopy, mutableCopyWithZone:, #nil?, open, p, #performSelector:onThread:withObject:waitUntilDone:, #performSelector:onThread:withObject:waitUntilDone:modes:, #performSelector:withObject:afterDelay:, #performSelector:withObject:afterDelay:inModes:, #performSelectorInBackground:withObject:, #performSelectorOnMainThread:withObject:waitUntilDone:, #performSelectorOnMainThread:withObject:waitUntilDone:modes:, print, printf, #private_methods, proc, #protected_methods, #public_method, #public_methods, #public_send, putc, puts, raise, rand, readline, readlines, #replacementObjectForCoder:, #replacementObjectForKeyedArchiver:, require, resolveClassMethod:, resolveInstanceMethod:, #respond_to?, #respond_to_missing?, select, #send, setVersion:, #singleton_methods, sprintf, srand, superclass, #taint, #tainted?, #tap, test, throw, #to_plist, trace_var, trap, #trust, #untaint, untrace_var, #untrust, #untrusted?, version

Constructor Details

This class inherits a constructor from NSObject

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class NSObject

Class Method Details

+ (Proc) new {|...| ... } + (Proc) new

Creates a new Proc object, bound to the current context. Proc::new may be called without a block only within a method with an attached block, in which case that block is converted to the Proc object.

def proc_from
  Proc.new
end
proc = proc_from { "hello" }
proc.call   #=> "hello"

Overloads:

  • + new {|...| ... }

    Yields:

    • (...)

    Returns:

  • + new

    Returns:

Instance Method Details

- (Boolean) ==(other_proc)

Returns true if prc is the same object as other_proc, or if they are both procs with the same body.

Returns:

  • (Boolean)

- (Object) call(params, ...) - (Object) [](params, ...)

Invokes the block, setting the block's parameters to the values in params using something close to method calling semantics. Generates a warning if multiple values are passed to a proc that expects just one (previously this silently converted the parameters to an array). Note that prc.() invokes prc.call() with the parameters given. It's a syntax sugar to hide "call".

For procs created using lambda or ->() an error is generated if the wrong number of parameters are passed to a Proc with multiple parameters. For procs created using Proc.new or Kernel.proc, extra parameters are silently discarded.

Returns the value of the last expression evaluated in the block. See also Proc#yield.

a_proc = Proc.new {|a, *b| b.collect {|i| i*a }}
a_proc.call(9, 1, 2, 3)   #=> [9, 18, 27]
a_proc[9, 1, 2, 3]        #=> [9, 18, 27]
a_proc = lambda {|a,b| a}
a_proc.call(1,2,3)

produces:

prog.rb:4:in `block in <main>': wrong number of arguments (3 for 2) (ArgumentError)
  from prog.rb:5:in `call'
  from prog.rb:5:in `<main>'

Overloads:

- (Object) call(params, ...) - (Object) [](params, ...)

Invokes the block, setting the block's parameters to the values in params using something close to method calling semantics. Generates a warning if multiple values are passed to a proc that expects just one (previously this silently converted the parameters to an array). Note that prc.() invokes prc.call() with the parameters given. It's a syntax sugar to hide "call".

For procs created using lambda or ->() an error is generated if the wrong number of parameters are passed to a Proc with multiple parameters. For procs created using Proc.new or Kernel.proc, extra parameters are silently discarded.

Returns the value of the last expression evaluated in the block. See also Proc#yield.

a_proc = Proc.new {|a, *b| b.collect {|i| i*a }}
a_proc.call(9, 1, 2, 3)   #=> [9, 18, 27]
a_proc[9, 1, 2, 3]        #=> [9, 18, 27]
a_proc = lambda {|a,b| a}
a_proc.call(1,2,3)

produces:

prog.rb:4:in `block in <main>': wrong number of arguments (3 for 2) (ArgumentError)
  from prog.rb:5:in `call'
  from prog.rb:5:in `<main>'

Overloads:

- (Fixnum) arity

Returns the number of arguments that would not be ignored. If the block is declared to take no arguments, returns 0. If the block is known to take exactly n arguments, returns n. If the block has optional arguments, return -n-1, where n is the number of mandatory arguments. A proc with no argument declarations is the same a block declaring || as its arguments.

Proc.new {}.arity          #=>  0
Proc.new {||}.arity        #=>  0
Proc.new {|a|}.arity       #=>  1
Proc.new {|a,b|}.arity     #=>  2
Proc.new {|a,b,c|}.arity   #=>  3
Proc.new {|*a|}.arity      #=> -1
Proc.new {|a,*b|}.arity    #=> -2
Proc.new {|a,*b, c|}.arity    #=> -3

Returns:

- (Binding) binding

Returns the binding associated with prc. Note that Kernel#eval accepts either a Proc or a Binding object as its second parameter.

def fred(param)
  proc {}
end

b = fred(99)
eval("param", b.binding)   #=> 99

Returns:

- (Object) call(params, ...) - (Object) [](params, ...)

Invokes the block, setting the block's parameters to the values in params using something close to method calling semantics. Generates a warning if multiple values are passed to a proc that expects just one (previously this silently converted the parameters to an array). Note that prc.() invokes prc.call() with the parameters given. It's a syntax sugar to hide "call".

For procs created using lambda or ->() an error is generated if the wrong number of parameters are passed to a Proc with multiple parameters. For procs created using Proc.new or Kernel.proc, extra parameters are silently discarded.

Returns the value of the last expression evaluated in the block. See also Proc#yield.

a_proc = Proc.new {|a, *b| b.collect {|i| i*a }}
a_proc.call(9, 1, 2, 3)   #=> [9, 18, 27]
a_proc[9, 1, 2, 3]        #=> [9, 18, 27]
a_proc = lambda {|a,b| a}
a_proc.call(1,2,3)

produces:

prog.rb:4:in `block in <main>': wrong number of arguments (3 for 2) (ArgumentError)
  from prog.rb:5:in `call'
  from prog.rb:5:in `<main>'

Overloads:

- (Object) clone

:nodoc:

- (Proc) curry - (Proc) curry(arity)

Returns a curried proc. If the optional arity argument is given, it determines the number of arguments. A curried proc receives some arguments. If a sufficient number of arguments are supplied, it passes the supplied arguments to the original proc and returns the result. Otherwise, returns another curried proc that takes the rest of arguments.

b = proc {|x, y, z| (x||0) + (y||0) + (z||0) }
p b.curry[1][2][3]           #=> 6
p b.curry[1, 2][3, 4]        #=> 6
p b.curry(5)[1][2][3][4][5]  #=> 6
p b.curry(5)[1, 2][3, 4][5]  #=> 6
p b.curry(1)[1]              #=> 1

b = proc {|x, y, z, *w| (x||0) + (y||0) + (z||0) + w.inject(0, &:+) }
p b.curry[1][2][3]           #=> 6
p b.curry[1, 2][3, 4]        #=> 10
p b.curry(5)[1][2][3][4][5]  #=> 15
p b.curry(5)[1, 2][3, 4][5]  #=> 15
p b.curry(1)[1]              #=> 1

b = lambda {|x, y, z| (x||0) + (y||0) + (z||0) }
p b.curry[1][2][3]           #=> 6
p b.curry[1, 2][3, 4]        #=> wrong number of arguments (4 for 3)
p b.curry(5)                 #=> wrong number of arguments (5 for 3)
p b.curry(1)                 #=> wrong number of arguments (1 for 3)

b = lambda {|x, y, z, *w| (x||0) + (y||0) + (z||0) + w.inject(0, &:+) }
p b.curry[1][2][3]           #=> 6
p b.curry[1, 2][3, 4]        #=> 10
p b.curry(5)[1][2][3][4][5]  #=> 15
p b.curry(5)[1, 2][3, 4][5]  #=> 15
p b.curry(1)                 #=> wrong number of arguments (1 for 3)

b = proc { :foo }
p b.curry[]                  #=> :foo

Overloads:

  • - curry

    Returns:

  • - curry

    Returns:

- (Object) dup

:nodoc:

- (Boolean) ==(other_proc)

Returns true if prc is the same object as other_proc, or if they are both procs with the same body.

Returns:

  • (Boolean)

Returns:

  • (Boolean)

- (Integer) hash

Returns a hash value corresponding to proc body.

Returns:

- (Boolean) lambda?

Returns true for a Proc object for which argument handling is rigid. Such procs are typically generated by lambda.

A Proc object generated by proc ignores extra arguments.

proc {|a,b| [a,b] }.call(1,2,3)    #=> [1,2]

It provides nil for missing arguments.

proc {|a,b| [a,b] }.call(1)        #=> [1,nil]

It expands a single array argument.

proc {|a,b| [a,b] }.call([1,2])    #=> [1,2]

A Proc object generated by lambda doesn't have such tricks.

lambda {|a,b| [a,b] }.call(1,2,3)  #=> ArgumentError
lambda {|a,b| [a,b] }.call(1)      #=> ArgumentError
lambda {|a,b| [a,b] }.call([1,2])  #=> ArgumentError

Proc#lambda? is a predicate for the tricks. It returns true if no tricks apply.

lambda {}.lambda?            #=> true
proc {}.lambda?              #=> false

Proc.new is the same as proc.

Proc.new {}.lambda?          #=> false

lambda, proc and Proc.new preserve the tricks of a Proc object given by & argument.

lambda(&lambda {}).lambda?   #=> true
proc(&lambda {}).lambda?     #=> true
Proc.new(&lambda {}).lambda? #=> true

lambda(&proc {}).lambda?     #=> false
proc(&proc {}).lambda?       #=> false
Proc.new(&proc {}).lambda?   #=> false

A Proc object generated by & argument has the tricks

def n(&b) b.lambda? end
n {}                         #=> false

The & argument preserves the tricks if a Proc object is given by & argument.

n(&lambda {})                #=> true
n(&proc {})                  #=> false
n(&Proc.new {})              #=> false

A Proc object converted from a method has no tricks.

def m() end
method(:m).to_proc.lambda?   #=> true

n(&method(:m))               #=> true
n(&method(:m).to_proc)       #=> true

define_method is treated the same as method definition. The defined method has no tricks.

class C
  define_method(:d) {}
end
C.new.d(1,2)       #=> ArgumentError
C.new.method(:d).to_proc.lambda?   #=> true

define_method always defines a method without the tricks, even if a non-lambda Proc object is given. This is the only exception for which the tricks are not preserved.

class C
  define_method(:e, &proc {})
end
C.new.e(1,2)       #=> ArgumentError
C.new.method(:e).to_proc.lambda?   #=> true

This exception insures that methods never have tricks and makes it easy to have wrappers to define methods that behave as usual.

class C
  def self.def2(name, &body)
    define_method(name, &body)
  end

  def2(:f) {}
end
C.new.f(1,2)       #=> ArgumentError

The wrapper def2 defines a method which has no tricks.

Returns:

  • (Boolean)

Returns:

  • (Boolean)

- (Proc) to_proc

Part of the protocol for converting objects to Proc objects. Instances of class Proc simply return themselves.

Returns:

- (Object) to_s

- (Object) call(params, ...) - (Object) [](params, ...)

Invokes the block, setting the block's parameters to the values in params using something close to method calling semantics. Generates a warning if multiple values are passed to a proc that expects just one (previously this silently converted the parameters to an array). Note that prc.() invokes prc.call() with the parameters given. It's a syntax sugar to hide "call".

For procs created using lambda or ->() an error is generated if the wrong number of parameters are passed to a Proc with multiple parameters. For procs created using Proc.new or Kernel.proc, extra parameters are silently discarded.

Returns the value of the last expression evaluated in the block. See also Proc#yield.

a_proc = Proc.new {|a, *b| b.collect {|i| i*a }}
a_proc.call(9, 1, 2, 3)   #=> [9, 18, 27]
a_proc[9, 1, 2, 3]        #=> [9, 18, 27]
a_proc = lambda {|a,b| a}
a_proc.call(1,2,3)

produces:

prog.rb:4:in `block in <main>': wrong number of arguments (3 for 2) (ArgumentError)
  from prog.rb:5:in `call'
  from prog.rb:5:in `<main>'

Overloads: