From: Im still <quietstill@...>
Date: 2009-08-20T12:08:10+09:00
Subject: Re: Class name as a variable

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2009/8/20 spox <spox@modspox.com>

> On Wednesday 19 August 2009 12:07:06 pm Im still wrote:
> > Hi all
> >
> > I'm thinking about a question, that is : Several classes will have a
> method
> > in a same name (probably do same thing too).
> > then in a program I want the method calling class name coming from a
> > variable( or maybe a result of a expr).
> >
> > for example:
> >
> >     class A
> >       def abc end
> >     end
> >
> >     class B
> >       def abc end
> >     end
> >
> >     #what i want to do is something like
> >
> >     a = a_variable.abc   # a_variable = A | B
> >
> > Now I'm doing this by
> >
> >    a = eval(" #{a_variable}.abc ")
> >
> > My question is, is there any better (or nicer) way to doing this?
> >
> > Thanks :)
>
> With how you asked your question, I'm assuming you want to call a static
> method. Otherwise, what's the point of the eval. So, is something like this
> what you are after:
>
> class A
>        def A.abc
>                "fu"
>        end
> end
> class B
>        def B.abc
>                "bar"
>        end
> end
>
> With this, there are a couple ways to do this. One, have your variable hold
> the constant:
>
> var = A
> var.abc -> "fu"
> var = B
> var.abc -> "bar"
>
> If the variable holds the class name as a string, or symbol, you can fetch
> the
> constant:
>
> var = 'A'
> Kernel.const_get(var).abc -> "fu"
> var = :B
> Kernel.const_get(var).abc -> "bar"
>
>
> ==============

Hi Spox
Ye, they should be static methods, else it will be wrong. My mistake :DThanks
very much, what you told is exactly what I want !

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