From: Jeremy Kemper <jeremy@...>
Date: 2010-03-27T05:30:00+09:00
Subject: [ruby-core:29051] Re: [Feature #889] erb.rb should use Array and << 	for eoutvar and not String and concat

On Fri, Mar 26, 2010 at 11:45 AM, Kurt  Stephens <redmine@ruby-lang.org> wrote:
> Issue #889 has been updated by Kurt �Stephens.
>
>
> This is not a good idea, because the expression value Strings accumulated in the Array must be protected from mutation.
> ERB expressions can have side-effects.
>
> <pre>
> SOME_STRING = 'foobar'
> def foo
> �SOME_STRING
> end
> def bar
> �SOME_STRING.sub!(/bar/, '')
> �SOME_STRING
> end
> # ERB GENERATED CODE: from "<%= foo %><%= bar %>"
> eoutvar = [ ]
> eoutvar << foo
> eoutvar << bar
> eoutvar.join('')
> </pre>

I disagree. That's based on a loose assumption that <%= ... %> behaves
like #{...}.

But all it says is "output" not necessarily "interpolate" -- that's a
side effect of the current implementation. Much like using <% .... #
comment %> was an assumption that later broke.

jeremy