Proc (Procdures)

  • A Proc object is an encapsulation of a block of code, which can be stored in a local variable, passed to a method or another Proc, and can be called.

Example 1#

square = Proc.new {|x| x**2 }
square.call(3) #=> 9
# shorthands:
square.(3) #=> 9
square[3] #=> 9

Example 2#

def gen_times(factor)
Proc.new {|n| n*factor } # remembers the value of factor at the moment of creation
end
times3 = gen_times(3)
times5 = gen_times(5)
times3.call(12) #=> 36
times5.call(5) #=> 25
times3.call(times5.call(4)) #=> 60

Procs with multiple params:#

def test_method
Proc.new do |var_a, var_b|
p "varA #{var_a}: varB: #{var_b}"
end
end
temp = test_method
temp.call(1,2)
# Output:
$ruby main.rb
"varA 1: varB: 2"

Procs doesn't throw an error when wrong numbers of variables are passed#

def test_method
Proc.new do |var_a, var_b|
p "varA #{var_a}: varB: #{var_b}"
end
end
temp = test_method
temp.call(1)
# Output:
$ruby main.rb
"varA 1: varB: "

TODO: try to do something after Proc.new

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