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Posted by Uri Guttman on July 18, 2008, 12:11 pm
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BM> guaranteed: since explicitly passing a scalar ref to a function is
BM> rather unusual (though not unknown), I would wager that is the case.
passing scalar refs is very useful and not just to modify things. if you
are passing around large strings/buffers, passing by ref is much more
efficient (assuming you copy args out of @_). you may not use scalar
refs as often a hash/array refs but they should be part of your
toolkit. you just need to be creative to find times where they help out.
uri
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Uri Guttman ------ uri@stemsystems.com -------- http://www.sysarch.com --
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Posted by Uri Guttman on July 17, 2008, 11:30 pm
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>> Huh? The sub defaults to operating on $_ if no argument is supplied.
>> That's hardly an 'edge case'.
JD> What sub? Here's the original code:
JD> my($text) = @_;
JD> if ($text)
JD> {
JD> $$text =~ s/^\s+//;
JD> $$text =~ s/\s+$//;
JD> }
JD> else
JD> {
JD> s/^\s+//;
JD> s/\s+$//;
JD> }
JD> This means that if the first argument evaluates to "false" (which is
JD> not at all the same as "not supplying an argument"), the else clause is
JD> executed and $_ is modified. IMHO that seems like very sloppy and
JD> unusual coding.
but notice $text is supposed to be a scalar ref. so if no arg is passed
in, the sub works on $_. if $text is set, it works on the scalar
value. if $text isn't a scalar ref it dies.
this is the guts from some kiddie's trim sub which take a ref to a
scalar to trim or defaults to working on $_. not something i would ever
write like that. well, in general i don't use $_ unless i have to. i
like named variables.
uri
--
Uri Guttman ------ uri@stemsystems.com -------- http://www.sysarch.com --
----- Perl Code Review , Architecture, Development, Training, Support ------
--------- Free Perl Training --- http://perlhunter.com/college.html ---------
--------- Gourmet Hot Cocoa Mix ---- http://bestfriendscocoa.com ---------
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