From: "Wolfgang Nádasi-Donner" <wonado@...>
Date: 2007-01-23T05:00:10+09:00
Subject: Re: Bug in Ruby with adding strings?

Gregory Brown schrieb:
> it may be parsing as 'foo' + x.to_s(+'bar') since to_s can sometimes
> take an argument.

This makes sense. When translating the infix notation to method usage (don't 
know if this will be done by the interpreter), the first step is

'foo' + x.to_s +'bar' => 'foo'.+(x.to_s +'bar')

"String#+" has one argument, so "x.to_s +'bar'" must be one argument. When 
looking to "x" it is not clear for the interpreter, what the result of "x.to_s" 
will be, but it knows, that "to_s" has an (optional) argument.

So it tries to find "String#+@" method for 'bar' and fails.

The possibility to backtrack after failure and try first to evaluate "x.to_s", 
which returns the string "'1'", an then to compute "'1' +'bar'" (works without 
any problem) will not be done due to good reasons for the general case.

Wolfgang N�dasi-Donner