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method

# arity

v2_5_5 - Show latest stable - 0 notes - Class: Method
`arity()` public

Returns an indication of the number of arguments accepted by a method. Returns a nonnegative integer for methods that take a fixed number of arguments. For Ruby methods that take a variable number of arguments, returns -n-1, where n is the number of required arguments. Keyword arguments will be considered as a single additional argument, that argument being mandatory if any keyword argument is mandatory. For methods written in C, returns -1 if the call takes a variable number of arguments.

```class C
def one;    end
def two(a); end
def three(*a);  end
def four(a, b); end
def five(a, b, *c);    end
def six(a, b, *c, &d); end
def seven(a, b, x:0); end
def eight(x:, y:); end
def nine(x:, y:, **z); end
def ten(*a, x:, y:); end
end
c = C.new
c.method(:one).arity     #=> 0
c.method(:two).arity     #=> 1
c.method(:three).arity   #=> -1
c.method(:four).arity    #=> 2
c.method(:five).arity    #=> -3
c.method(:six).arity     #=> -3
c.method(:seven).arity   #=> -3
c.method(:eight).arity   #=> 1
c.method(:nine).arity    #=> 1
c.method(:ten).arity     #=> -2

"cat".method(:size).arity      #=> 0
"cat".method(:replace).arity   #=> 1
"cat".method(:squeeze).arity   #=> -1
"cat".method(:count).arity     #=> -1```
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