From: Florian Gross <flgr@...>
Date: 2003-10-16T08:00:04+09:00
Subject: Re: General Ruby Programming questions

Simon Kitching wrote:

> Hi,

Moin!

> I have a string containing the name of a class, and want to get the
> corresponding Class object. My current approach is:
>   Module.class_eval(classname)
> Is this the best approach?

It isn't -- an user might inject arbitary code. Use this instead:

irb(main):001:0> Object.const_get('Class')
=> Class

> (b) changing "require" searchpath
> The $: variable holds the path used to locate files when the "require"
> command is used. However this variable is read-only. In Perl, it is
> possible to modify the equivalent path; can this be done in ruby?

It might be read-only, but that doesn't mean that you can't change the 
object which it refers to:

irb(main):002:0> $:.push('new')
=> [..., 'new']

> (c) how invoke "hidden" methods?

Simply send the message a method invocation would produce yourself:

irb(main):003:0> 5.send(:rand)
=> 0.748920713318512

> (d) iterating in reverse 
> I have an Array object, and wish to iterate over its members in reverse.
> I would prefer not to have to create a new Array object in order to do
> this iteration. Is there any way other than writing

irb(main):004:0> [1, 2, 3].reverse_each { |item| puts item }
3
2
1

Regards,
Florian Gro�