Beefy Boxes and Bandwidth Generously Provided by pair Networks
Pathologically Eclectic Rubbish Lister
 
PerlMonks  

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

by faq_monk (Initiate)
on Oct 08, 1999 at 00:20 UTC ( [id://606]=perlfaq nodetype: print w/replies, xml ) Need Help??

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

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:

    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 = $old;
    somefunc($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:

    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.

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

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others meditating upon the Monastery: (5)
As of 2024-03-29 08:41 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found