Calling a Variable from another file

monkfan has asked for the wisdom of the Perl Monks concerning the following question:

For example I have a hash created with Data::Dumper, stored in a variable $res, in a file called "mydata.pl"

use strict;
#File name: mydata.pl

my $res = {
       # a very big hash reference
       # created with Data::Dumper
       # with a very long processing time
};
[download]

And I would like to use that variable for my "main.pl" file.
Can we do that? Just as we call a function. I hope that`s a reasonable question. Thanks beforehand.

Regards,
Edward

Comment on Calling a Variable from another file Download Code

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Re: Calling a Variable from another file by tlm (Prior) on Jun 22, 2005 at 13:47 UTC
I've never actually done what I'm about to propose, so there may be pitfalls I haven't thought of, but assuming that the assignment to `my $res` is the last executable statement in `mydata.pl`, I would try something like `my $whatever = do 'mydata.pl';` [download] That should be equivalent to assigning to `$whatever` the value returned by `eval`'ing the contents of `mydata.pl`. I question the whole approach on design grounds, however. See this thread for some possible alternatives. the lowliest monk	[reply] [d/l]
Re: Calling a Variable from another file by davidrw (Prior) on Jun 22, 2005 at 13:43 UTC
This isn't really the best way to store/pull back stuff, but it is quick & dirty (basically just eval your $res string): `# storing: my $data = ... ; # some big hairy data structure open FILE, ">$filename" or die "can't open '$filename': $!"; print FILE Dumper($data); close FILE; # retrieving: open FILE, "$filename" or die "can't open '$filename': $!"; my $VAR1; eval do{ local $/=undef; <FILE> }; # your big hairy data structure is in $VAR1 now close FILE;` [download] You can also play with the Data::Dumper syntax so that the string had "$data =" instead of "$VAR1 =".	[reply] [d/l]
Re: Calling a Variable from another file by halley (Prior) on Jun 22, 2005 at 13:44 UTC
The `my` keyword makes the variable into a private "lexical" variable. Code in other packages cannot refer to it by name. The `our` keyword works similarly, but turns the name into a package variable. Then you can refer to it by its package. For example, if declared inside `package MyPackageName`, then other packages can refer to it as `$MyPackageName::res`. I could just tell you that files included with `require` don't need package names and all of that, but that path leads to madness when your project grows. -- `[ e d @ h a l l e y . c c ]`	[reply] [d/l] [select]