Beefy Boxes and Bandwidth Generously Provided by pair Networks
Clear questions and runnable code
get the best and fastest answer

asterisk use

by smist (Acolyte)
on Jan 10, 2007 at 19:19 UTC ( #593984=perlquestion: print w/ replies, xml ) Need Help??
smist has asked for the wisdom of the Perl Monks concerning the following question:

Hello. I'm using find2perl to generate some code and the code below that was generated doesn't make sense to me. What are the asterisks used for? I know I've seen something like this before but I cannot remember where and how it works. Thanks!
use vars qw/*name *dir *prune/; *name = *File::Find::name; *dir = *File::Find::dir; *prune = *File::Find::prune;

Comment on asterisk use
Download Code
Replies are listed 'Best First'.
Re: asterisk use
by davido (Archbishop) on Jan 10, 2007 at 19:26 UTC

    Those are typeglobs, and are being used to make aliases to variables embedded within the File::Find module.

    For example, $name will be an alias to $File::Find::name.

    That way, the package global, $name, which presumably resides in package main (otherwise known as $main::name) will be the same variable as $File::Find::name; a package global in the File::Find module.


      To slightly extend davido's explanation with a more concrete example (because that's how I learn anyway):

      This first example uses the full variable name to find all instances of mail.log.* in the current directory and pushes the results on @files.

      use File::Find; find( sub { push @files, $File::Find::name if -f && /mail.log.*/ }, '. +');

      This second example does the same thing only using the glob'd version of the variable name.

      use File::Find; use vars qw/*name/; *name = *File::Find::name; find( sub { push @files, $name if -f && /mail.log.*/ }, '.');
        In the subroutine named "wanted" that find2perl creates there is usage of the "&&" operator. If I understand it correctly, it's evaluating each expression, and if they evaluate to "true" it prints $name. Is the last "&&" necessary? There are no expressions after it; just goes to the print statement.

        sub wanted { my ($dev,$ino,$mode,$nlink,$uid,$gid); (($dev,$ino,$mode,$nlink,$uid,$gid) = lstat($_)) && -d _ && print("$name\n"); }
        Thanks guys. I knew I read about this somewhere before. I just couldn't remember what it was. I haven't used globbing yet and I'm pretty new to Perl.

        Your help is appreciated!
Re: asterisk use
by imp (Priest) on Jan 10, 2007 at 19:23 UTC

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: perlquestion [id://593984]
Approved by Corion
Front-paged by Corion
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others contemplating the Monastery: (3)
As of 2015-11-26 16:34 GMT
Find Nodes?
    Voting Booth?

    What would be the most significant thing to happen if a rope (or wire) tied the Earth and the Moon together?

    Results (703 votes), past polls