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

Jasmine
Administrator

Jan 19, 2001, 3:01 PM

Post #1 of 1 (1195 views)

What's wrong with always quoting "$vars"?	Can't Post

(From the Perl FAQ)

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.

If you get used to writing odd things like these:

Code

    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:

Code

    print $var; 
    $new = $old; 
    somefunc($var);

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 reference:

Code

    func(\@array); 
    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() function.

Stringification also destroys arrays.

Code

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

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