FAQ 4.37 What's wrong with always quoting "$vars"? #4 554308

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4.37: What's wrong with always quoting "$vars"?

    The problem is that those double-quotes force stringification--coercing
    numbers and references into strings--even when you don't want them to be
    strings. Think of it this way: double-quote expansion is used to produce
    new strings. If you already have a string, why do you need more?

    If you get used to writing odd things like these:

            print "$var";           # BAD
            $new = "$old";          # BAD
            somefunc("$var");       # BAD

    You'll be in trouble. Those should (in 99.8% of the cases) be the
    simpler and more direct:

            print $var;
            $new = $old;

    Otherwise, besides slowing you down, you're going to break code when the
    thing in the scalar is actually neither a string nor a number, but a

            sub func {
                    my $aref = shift;
                    my $oref = "$aref";  # WRONG

    You can also get into subtle problems on those few operations in Perl
    that actually do care about the difference between a string and a
    number, such as the magical "++" autoincrement operator or the syscall()

    Stringification also destroys arrays.

            @lines = `command`;
            print "@lines";     # WRONG - extra blanks
            print @lines;       # right


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brian125 (4408)
6/12/2006 7:03:03 AM
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