From: Brian Candler <b.candler@...>
Date: 2009-08-27T02:50:06+09:00
Subject: Re: ||= with 1.8 and 1.9 ?

7stud -- wrote:
> Rick Denatale wrote:
>>> a1 = A.new
>>> puts a1.x = 10
>>>
>>> a2 = A.new
>>> puts a2.x=(10)
>> 
>>> both versions return the same thing.
>> 
>> Because they are both using the assignment sugar. Parenthesizing the
>> 10 doesn't change that.
> 
> The method name is 'x=' and it was called using 'obj.x='.    Where's the
> sugar?

The parentheses in (10) are not delimiting arguments of a method call; 
they are just bracketing a value expression. Note:

>> class Foo; def bar=(x,y,z); 123; end; end
=> nil
>> Foo.new.send(:bar=,7,8,9)
=> 123
>> Foo.new.bar=(7,8,9)
SyntaxError: compile error
(irb):3: syntax error, unexpected ',', expecting ')'
Foo.new.bar=(7,8,9)
               ^
  from (irb):3
  from :0
>> 

Similarly:

>> Foo.new.bar= 7,8,9
ArgumentError: wrong number of arguments (1 for 3)
  from (irb):4:in `bar='
  from (irb):4
  from :0
>> 

The other way you can see it's sugar is that a space is allowed between 
x and =.
-- 
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