From: Justin Collins <collinsj@...>
Date: 2006-03-22T02:10:45+09:00
Subject: Re: ! and ? in function name

Tony wrote:
> Hi Ruby-rulez !
> 
> I often look at some code, for example un rails/active_record, where 
> functions name end with a ? or a !
> 
> Is this a special notation, meaning that the func or args or whatever 
> have some treatment before/after the body ? Or to show that the function 
> return a boolean (?) and the arg modified (!) ?
> 
> Thanx ;)

Generally the (?) means it returns a boolean and (!) means it modifies
the receiver (the object the method is being called on) in place, rather
than creating a new object.

For example:

irb(main):001:0> a = "Hello"
=> "Hello"
irb(main):002:0> a.include?('e')
=> true
irb(main):003:0> a.reverse
=> "olleH"
irb(main):004:0> a
=> "Hello"                     #unmodified
irb(main):005:0> a.reverse!
=> "olleH"                     #modified
irb(main):006:0> a
=> "olleH"


Hope that helps.

-Justin

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