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From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: Patterns vs Strings
Message-ID: <1991Feb08.034916.29904@convex.com>
Date: 8 Feb 91 03:49:16 GMT
References: <121642@uunet.UU.NET> <1991Feb07.210023.8308@convex.com> <121661@uunet.UU.NET>
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Reply-To: tchrist@convex.COM (Tom Christiansen)
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From the keyboard of rbj@uunet.UU.NET (Root Boy Jim):
:However, m'$var' == m"$var" == m`$var`. And tr is brain dead.
:I have to use eval to get vars into either side.

Well, I wouldn't call tr braindead just because it doens't
do something it's not documented to do.  

I think that this illustrates that single quotes DO matter:


    $_ = 'contains $foo in it';

    $foo = 'bar';
    print "match in singles: ", m'\$foo', "\n";
    print "match in doubles: ", m"$foo", "\n";
    print "match in   backs: ", m`$foo`, "\n";

    $foo = 'tain';
    print "foo is $foo\n";
    print "match in singles: ", m'\$foo', "\n";
    print "match in doubles: ", m"$foo", "\n";
    print "match in   backs: ", m`$foo`, "\n";


:However, once again, I have not made myself clear. I am talking
:about the first argument to split and join. Normally, you can't
:just go passing strings to functions/operators by /quoting/ with slashes.

I wouldn't say "normally" -- I would say "never"!  Putting /slashes/
around a string it a run-time pattern match against $_.  This:

    join(/foo/, 'a', 'bird', 'in', 'the', 'hand');

yields

    'a1bird1in1the1hand'

if you leave $_ at what it was above, and 

    'abirdinthehand'

in most other cases.

:And by "data types", I meant "string" vs "numeric". I know....

But those are just the same scalar data type, which is a wee bit 
polymorphic.  But this part might just be a matter of semantics.

--tom
--
 "All things are possible, but not all expedient."  (in life, UNIX, and perl)