From: Lionel Thiry <lthiry@...>
Date: 2004-10-15T07:51:49+09:00
Subject: Re: [nuby] shell-like substitution in a string

Hello!

Thanks for the help, but I can already handle the recursive expansion of 
the strings. My main problem is about the pattern itself, it gives me 
headaches.

Some comments follow.

Kaspar Schiess a �crit :

> Hello Lionel,
> 
> That was quite a quiz you asked us ;)
> 
> I have a solution using only 'regular' regular expressions, the one in
> 1.8.1. Thus: this solution works without oniguruma.
> 
> I work around the lookbehind trouble by appending three spaces in front
> of the string.
> 
> I am sure this solution is hideously complicated and can be improoved.
> Anyone ?
> 
> Here's the output:
> ~ bluna ${var\}weird}
> ~ bluna weird substitute
> 
> ~ sh ${tool} -o ${target} -L${libpath} -l${lib} ${source}
> ~ sh gcc -o test.exe -L/usr/lib -lopengl render.c
> 
> ~ \${var}
> ~ \${var}
I'd prefer '${var}' as a result, is it possible? Doesn't the (?>re) 
expression fit for that purpose? Or should I make some substitution 
after the match?

> 
> ~ \\${var}
> ~ \\rvar
> 
> ~ $\${var}
> ~ $\${var}
In fact, this case should generate an exception, as a non escaped $ 
should always be immediately followed by a {.

> 
> ~ $\$${var}
> ~ $\$rvar
Idem.
But "\\$${var}" should give "$rvar", ideal for letting the shell to make 
some postsubstitution with its usual env.

> 
> with an env of
> 
> ~ env = {
>     'var\}weird' => 'weird substitute',
>     'var' => 'rvar',
>     'tool' => 'gcc',
>     'target' => 'test.exe',
>     'libpath' => '/usr/lib',
>     'lib' => 'opengl',
>     'source' => 'render.c'
> ~ }
> 
> Hope this hits your nerv,
> kaspar
I still have a lot of work, but thanks for the help.

Lionel Thiry