Re: symbols in patterns interpreted *recursively*?

[Mike Ayers]

RLMuller wrote:
> Hi All,

        Hello!

> Using a pattern I encountered behavior I didn't expect, as follows:
>  
> my $ABC = "abc";
> $_ = $ABC;
> print "\$ABC     " . (/^$ABC$/? "matches" : "does not match") . " 
> \"$ABC\"\n";    # Matches
>  
> my $ABC_DEF = "abc\\def";
> $_ = $ABC_DEF;
> print "\$ABC_DEF " . (/^$ABC_DEF$/? "matches" : "does not match") . " 
> \"$ABC_DEF\"\n"; # Doesn't match
> print "abc\\def  " . (/^abc\\def$/? "matches" : "does not match") . " 
> \"abc\\def\"\n"; # Matches
>  
> If $ABC_DE's content is further interpreted, as seems to be the case, 
> how do I stop it?

	I'm feeling generous today, so I'm giving you not just an answer to 
your question, but two, count 'em, TWO helpful tips for a happy 
internet life!

        Answer:
print "\${ABC_DEF} " . (/^${ABC_DEF}$/? "matches" : "does not match") 
. " \"${ABC_DEF}\"\n"; # Matches!

	Note the brackets around the variable name, without which Perl will 
assume the variable name ends with the first nonalphanumeric 
character, in this case '_'.

        Suggestion 1:
	Don't send HTML, Rich text, or multipart MIME mail to technical 
mailing lists.  It just upsets people, and most likely the person who 
can best answer your question will be one of the upset parties.

        Suggestion 2:
	Send Perl questions to a Perl mailing list or newsgroup (heeding 
Suggestion 1 - I recommend comp.lang.perl.moderated).  Normally you 
will get no answer to them here.  I only looked at the problem because 
I thought it was a keyword substitution issue.

        ObCVS:
	Don't use Perl variables named $Name, $Id or any other CVS keyword if 
you want to be able to archive your script with CVS.


        Have a nice day,

/|/|ike