From: Daniel Berger <djberg96@...>
Date: 2009-06-12T22:55:07+09:00
Subject: Re: How to set $_ in a method?



> -----Original Message-----
> From: Bertram Scharpf [mailto:lists@bertram-scharpf.de]
> Sent: Friday, June 12, 2009 5:18 AM
> To: ruby-talk ML
> Subject: Re: How to set $_ in a method?
> 
> Hi,
> 
> Am Freitag, 12. Jun 2009, 16:45:51 +0900 schrieb Heesob Park:
> > I like to set caller's $_ variable in a method, but it did't work for
> me.
> > [...]
> > I noticed $_ is is local to the current scope.
> > Is it impossible to set the caller's $_ variable in a method without
> > using binding and eval?
> 
> $_ has some special meanings in Kernel.gets, Kernel.sub, Regexp#~
> etc. This comes in handy for -ne/-pe option oneliners. You
> shouldn't use it outside that (if you don't know what you do).

Except we're trying to match the zlib.c spec. Specifically,
rb_gzreader_gets() in zlib.c:

static VALUE
rb_gzreader_gets(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
    VALUE dst;
    dst = gzreader_gets(argc, argv, obj);
    if (!NIL_P(dst)) {
   rb_lastline_set(dst);
    }
    return dst;
}

The rb_lastline_set() call sets $_. What's the equivalent in pure Ruby? If
it's possible to do within a C extension, it ought to be possible to do in
pure Ruby.

Regards,

Dan