[EMAIL PROTECTED] wrote:
I see. Thanks Shawn. Since we are at it, would you mind explaining a little bit
about the significance of "our" keyword. I have never understood it properly.
Most books that I referred to say that it's a "lexically-scoped global
variable". What does that mean? I understand global variables to be the ones
which are accessible to all perl program units (modules, packages or scripts).
But then, what is so lexically-scoped about it? What do the perl compiler and
opcode interpreter do when encounter a variable name prefixed by "our"?
Below are three files, main, foo.pm, and bar.pm. These show the way 'my'
and 'our' behave.
A 'my' global variable is scoped only to the file it is in. It hides any
'our' variable (of the same name); you can only access the 'my'
variable. 'our' variables are global globals; they are the same and
accessible across files.
Below, you will note that the sub super_bar uses 'our' (in a block) to
override the 'my' definition of $Self to access the 'our' one. With
practice, you too can create code that is a nightmare for your maintainers.
#!/usr/bin/perl
use strict;
use warnings;
our $Self = __FILE__;
use foo;
use bar;
print "main: $Self\n";
foo();
bar();
super_bar();
__END__
# foo.pm
our $Self = __FILE__;
print "foo: $Self\n";
sub foo {
print "foo: $Self\n";
}
1;
__END__
# bar.pm
my $Self = __FILE__;
print "bar: $Self\n";
sub bar {
print "bar: $Self\n";
}
sub super_bar {
our $Self;
print "super_bar: $Self\n";
}
1;
__END__
--
Just my 0.00000002 million dollars worth,
--- Shawn
"Probability is now one. Any problems that are left are your own."
SS Heart of Gold, _The Hitchhiker's Guide to the Galaxy_
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