From: Ilmari Heikkinen <kig@...>
Date: 2005-01-25T01:48:57+09:00
Subject: Re: Complex Library Object/Class and its Interface

Aahhh and 10 seconds after I sent that, another way surfaced:

Parser::Token configurators could use define_method instead of 
@class_ivar, that way they'd be inherited.

Mmh. I'm not really happy with either of my suggestions. Oh well, may 
others have better ways.


On 24.1.2005, at 18:40, Ilmari Heikkinen wrote:

> Hi,
> On 24.1.2005, at 18:15, Trans wrote:
>
>> |class Marker < Parser::Token
>> |
>> |    exclusive false
>> |    start { %r{ \< (.*?) \> }mx }
>> |    stop { |match| %r{ \< [ ]* (#{esc(match[1])}) (.*?) \. \> }mx }
>> |
>> |    #... user's optional methods ...
>>
>> It toke me some time to work this out in itself. And I thought I had
>> finally gotten a fairly nice interface here. But to my dismay, I just
>> discovered that I can't subclass Marker b/c I loose the definitions of
>> the above attributes (ie. exclusive, start, stop). So now I'm back to
>> rethinking the whole setup. (Also note that if the user's methods
>> redefine #initialize or the other Token methods, it might cause the
>> parser that uses it to break --another slight down side and a possible
>> use case for RCR #198)
>>
>> So how does one properly build something like this in a nice neat way?
>>
>
> This is the first thought that entered my mind: turn the configuration 
> methods into instance methods, move the method calls to #initialize, 
> and call super there:
>
> class Marker < Parser::Token
>   def initialize
>     super
>     exclusive false
>     start { %r{ \< (.*?) \> }mx }
>     stop { |match| %r{ \< [ ]* (#{esc(match[1])}) (.*?) \. \> }mx }
>   end
> end
>
> class ExclusiveMarker < Marker
>   def initialize
>     super
>     exclusive true
>   end
> end
>
>
> Maybe that would work?
>
> --
> Ilmari Heikkinen
>
>
>