Style

camelCase is bad

Have you ever had to maintain someone else's code?

Have you ever had to maintain code like this?

    my $variableThatContainsData =
        someSubroutineThatMucksWithData( $someAwfulVariable );

The mixed-case-for-words is called camelCase in the Perl world, and it's generally frowned upon because it makes reading code difficult.

Even with the horrible names, using underscores makes things more readable:

    my $variable_that_contains_data =
        some_subroutine_that_mucks_with_data( $some_awful_variable );

warnings & strict

For any program you expect to maintain, reuse, or distribute (that is, for any program), you should have the following lines of code:

    #!/usr/bin/perl

    use strict;
    use warnings;

Although, if your Perl is older than 5.6, you need to do this instead:

    #!/usr/bin/perl -w

    use strict;

Enabling strict makes Perl complain about uncertain coding constructs, such as undeclared variables, barewords, and "soft" references. These warnings will cause Perl to die.

    #!/usr/bin/perl
    use strict;

    $foo = 4; # undeclared variable error
    $foo = Bar; # bareword error
    my $bat = "foo";
    print $$bat; # reference error

Enabling warnings makes Perl complain even more verbosely, but unlike strict, these complaints are not fatal under ordinary circumstances.

    #!/usr/bin/perl
    use warnings;
    $a + 0; # void context warning
            # name used once warning
            # undef warning
    print "program continued\n"; # prints

If you want warnings to be fatal, tell it so:

    use warnings FATAL => 'all';
    $a + 0; # void warning and then exits
    print "program continued\n"; # doesn't print

Want to contribute?

Submit a PR to github.com/petdance/perl101