arity

prc.arity â fixnum

Instance Public methods

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

proc   { |x = 0| }.arity       #=> 0
lambda { |a = 0| }.arity       #=> -1
proc   { |x=0, y| }.arity      #=> 0
lambda { |x=0, y| }.arity      #=> -2
proc   { |x=0, y=0| }.arity    #=> 0
lambda { |x=0, y=0| }.arity    #=> -1
proc   { |x, y=0| }.arity      #=> 1
lambda { |x, y=0| }.arity      #=> -2
proc   { |(x, y), z=0| }.arity #=> 1
lambda { |(x, y), z=0| }.arity #=> -2

doc_ruby_on_rails

2015-04-28 15:23:00

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