From: _Kevin <kevin.olbrich@...>
Date: 2006-12-21T09:25:06+09:00
Subject: Re: reflecting on objects without creating one

Thanks guys,

_Kevin

Ezra Zygmuntowicz wrote:
> On Dec 20, 2006, at 1:53 PM, Justin Bailey wrote:
>
> > On 12/20/06, _Kevin <kevin.olbrich@gmail.com> wrote:
> >>
> >> Let's say I have two constants
> >>
> >> a = Integer
> >> b = Numeric
> >>
> >> Does anyone have any idea how to see if 'a' is a subclass of 'b'
> >> WITHOUT creating an object of class 'a'?
> >
> >
> > irb(main):021:0> a = Numeric
> > => Numeric
> > irb(main):022:0> b = Integer
> > => Integer
> > irb(main):023:0> a.ancestors
> > => [Numeric, Comparable, Object, Kernel]
> > irb(main):024:0> a.ancestors.include? b
> > => false
> > irb(main):025:0> b.ancestors.include? a
> > => true
> > irb(main):026:0>
> >
> > "b.ancestors.include? a" seems to do it. Notice I reversed your
> > definitions
> > of "a" & "b" (not for any particular reason, that's just how it
> > worked out).
> >
> > Justin
>
> You can also use < and > to compare subclasses or superclasses
>
> ez $ irb
>  >> a = Integer
> # => Integer
>
>  >> b = Numeric
> # => Numeric
>
>  >> a < b
> # => true
>
>  >> a > b
> # => false
>
>
> Cheers-
>
> -- Ezra Zygmuntowicz
> -- Lead Rails Evangelist
> -- ez@engineyard.com
> -- Engine Yard, Serious Rails Hosting
> -- (866) 518-YARD (9273)