From: "Shot (Piotr Szotkowski)" <shot@...>
Date: 2009-09-01T19:34:47+09:00
Subject: Re: help on phps $$ equivalent in ruby

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Arthur Rats:

> fields =3D [["somthing"]]

> fields.each{|x|
>   eval "#{x[0]} =3D Someclass::Somemethod.new"
> }

> puts something.text=3D"asdfasdfasdf"

> text is method from the Somthingclass that should
> work, but I get undefined variable for something.text

Others answered why it=E2=80=99s bad to use eval in this scenario (as it is
is most scenarios where it can be avoided), I=E2=80=99ll answer why the abo=
ve
doesn=E2=80=99t work: by calling eval inside the each block you=E2=80=99re =
creating
block-local variables which disappear right after you leave the block
(i.e., on the eval=E2=80=99s closing curly brace).

As for why using eval "@#{x[0]} =3D =E2=80=A6" works =E2=80=93 in this exam=
ple you=E2=80=99re
creating instance variables on the current object, and these live on
after the block ends.

=E2=80=94 Shot
--=20
>> The Ruby community should proceed with all deliberate
>> speed towards ISO standardization of the language.
> Yeah, look what it did to Forth.
Don=E2=80=99t just say it, show it. http://vividpicture.com/aleks/atari/for=
th.jpg
        [M. Edward (Ed) Borasky, Matt Lawrence, Gregory Brown, ruby-talk]

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