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

(this is a question about perl 5.003) i'm trying to "improve" existing code, and adding 'use strict;'

unfortunately one of the variables is set in an "include" file which is pulled by 'require'. Can I make this work? E.g.

==== main.pl ====

use strict;
my $ReqVar;
my $LocVar;
require include_file.pl;

$LocVar = $ReqVar;

<<at this point I'd like $LocVar to be foo,
but when strict and my are used $LocVar is blank
although it IS set to foo when 'my' is omitted>>

==== end of main.pl ====


==== include_file.pl ====

$ReqVar = "foo";
1;

==== end of _include_file.pl ====

thanks for hints -- I've read APP for 'strict' and 'require' and don't know if there's actually a solution. I'm constrained by this being existing code, which works when 'strict' and 'my' are not used. (It looks like 'our' in 5.6 would do this, but we're stuck at 5.003)

Alan

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Re: scope / strict / my / require
by dave_the_m (Monsignor) on Jul 23, 2004 at 23:02 UTC
    Replace 
        my $ReqVar;

    [download]
    with 
        use vars qw($ReqVar);

    [download]
    This is the nearest equialent 5.003 has to 'our'.

    Dave.

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Re: scope / strict / my / require
by davido (Cardinal) on Jul 24, 2004 at 04:40 UTC

    The facts:

    In your code examples, it looks like include_file.pl is not set up as a separate package; it is just another file containing more code that comprises package main. I just mention that because it's relevant to the rest of this post.

    $ReqVar, as defined in include_file.pl, is a package global that exists in package main, introduced by virtue of 'require' pulling it in from an external file. So far so good (though a little arcane). $ReqVar, because it's a package global in package main is really just a shorthand way of expressing what the variable is really named. Its real name is $main::ReqVar.

    Next you use 'my' to declare a lexical variable in the main portion of your script. That lexical variable is named $ReqVar. Lexical variables are not package variables. Thus, they don't 'stand for' some other more fully qualified name. The lexical $ReqVar is a different variable from the package global named $main::ReqVar. The fact is that since the package global $main::ReqVar can be abbreviated as just $ReqVar, it is common to say that the lexical $ReqVar masks the package global $ReqVar (unless you refer to the package global by its fully qualified name, $main::$ReqVar

    That's a mouthfull. But let's demonstrate it another way: 

    $var1 = 100;
$var2 = 200;
{
    # The brackets just created a narrower lexical scope.
    my $var1 = "ABCDE";
    print "Inside the narrow lexical block:  $var1, $var2\n";
    print "The package global \$main::var still contains $main::var\n"
+;
}
# The } bracket just closed the narrow lexical block.
print "Outside the narrow lexical block: $var1, $var2\n";
__OUTPUT__
Inside the narrow lexical block:  ABCDE, 200
The package global $main::var still contains 100
Outside the narrow lexical block:  100, 200

    [download]

    The quick-fix solution for your specific case is either to put the line, use vars qw/ReqVar/; in your main script, instead of creating a lexical named $ReqVar, or to say my $LocVar = $main::ReqVar; instead, and not even bother with creating a lexical named $ReqVar.


    Dave

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Re: scope / strict / my / require
by Fletch (Bishop) on Jul 24, 2004 at 00:37 UTC
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