> -----Original Message-----
> From: David T-G [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, June 12, 2002 9:40 AM
> To: perl beginners
> Subject: "lazy" variable declaration
>
>
> Hi, all --
>
> I'm trying to be good and so I use "my $variable" rather than
> making them
> global, and I prefer to not stick little [potentially-confusing] "my"
> declarations around through the code so I declare my vars up front.
> While some of them might usefully be pre-filled, many of them
> can happily
> by left declared but undefined, so things like
>
> my $foo, $bar, $baz ;
This does not declare $bar and $baz to be "my" vars. "use strict"
will barf on this. Here the comma is the sequence operator, not
the list separator. You need:
my ($foo, $bar, $baz);
> my ($foo, $bar, $baz) = "" ;
This only initializes $foo. $bar and $baz are undef. To initialize
all 3, use a list:
my ($foo, $bar, $baz) = ('', '', '');
>
> work nicely. I haven't yet figured out, though, all of the rules for
> arrays and hashes. In my current script, I have
>
> my # vars we will use
> (
> $m3u, # file name
> $mp3, # disk label
> $source,$host, # where we got it
> $artist,$disk,$track, # the
> real data :-)
> @allsources, @allhosts, # where we get 'em
> $fullpath, # hash key
> @working, # stripped copy
> of $fullpath
> %threez, # hash that
> holds DB record
> ) = "" ;
>
> $m3u = $source = $host = "" ; # what
> can't be undef
>
> with the second line since those vars cause problems later if they are
> undefined (even though I set the vars to empty at declaration
> time just
> above) and, more importantly, have to put the hash at the end
> or I get an
> "odd number of elements added to hash" error.
The single initializer value goes only to the first variable.
If the first variable is a hash, you get the warning because
a hash should have an even number of key/value pairs in an
assignment.
>
> Since the code is meant to be clear and self-documenting, I
> don't have to
> have all of those comments on the right, and would prefer to
> just have a
> nice, polite "my" line listing everything and being done with it. Is
> there any way to mix all of these together?
Try the following:
my (@foo, @bar) = qw(a b c d);
print "\@foo is [@foo]\n";
print "\@bar is [@bar]\n";
This prints:
@foo is [a b c d]
@bar is []
Note that @foo "sucked up" all the values in the initializer list.
So there's really no way to initialize @foo to [a b] and @bar to [c d]
in a single statement like this.
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
