From: Philipp Meier <meier@...>
Date: 2002-09-30T07:24:52+09:00
Subject: Re: thoughts on typelessness


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On Sun, Sep 29, 2002 at 12:09:32PM +0900, dblack@candle.superlink.net wrote:
> You can also do this:
>=20
>    begin
>      a.meth
>    rescue NameError
>      ...
>=20
> I've done that, for instance, in my dbdbd (database definer) program.
> It uses 1-originating array notation to index columns, but can also
> use field-names.  So the reader method for the sort_key (for example)
> is:
>=20
>    def sort_key
>      @sort_key - 1
>    rescue NameError
>      @sort_key
>    end
>=20
> which I think looks better than:
>=20
>    def sort_key
>      if @sort_key.respond_to?(:-)
>        @sort_key - 1
>      else
>        @sort_key
>      end
>    end
>=20
> or any of the many variants of that.  But the rescue version is
> relatively slow.

I the NameError acutally might be thrown _inside_ @sort_key.- , because
of an programming error e.g., not because the the method does not exist.
So you must at least check for Exepction.backtrace.size =3D=3D 1.

-billy.

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