why 'Undefined subroutine'?

[katharnakh]

hi,

I was exercising package creation and its usage in Perl. I started with a simple program,
1. Created a package called A
2. Created a package called B
3. A program which includes those packages, and uses its services.

# A.pm
package A;
use warnings;

my $l_var = 10;		# lexically scoped variable
$g_var = 20;			# global variable

sub print_arg{
	my $v = shift;
	print "\nyou passed: $v\n";
}

sub sum{
	my ($var1, $var2) = @_;
	@cal = caller;
	print "\nfunc2: im called by, $cal[0]::$cal[1] at $cal[2]";
	
	return $var1+$var2;
}
	
#$res = func2(1,1);
	
1;

# B.pm
package B;
use warnings;

$b = 'package  B';

sub fib{
	my $range = shift;
	($a, $b) = (0, 1);
	while($b<$range){
		print "$b ";
		($a, $b) = ($b, $b+$a);
	}
}

#fib(30);

1;

# demo_package_test.pl
use A;
use B;

A::print_arg('this is an arg.');
my $res = A::sum(10, $A::g_var);
print "\nres = $res";

print "\n---\nb = $B::b";
&B::fib(50);

Output:

you passed: this is an arg.

func2: im called by, main::test_package.pl at 7
res = 30
---
b = Undefined subroutine &B::fib called at test_package.pl line 11.

I dont understand, why im not able to call a function which is defined in the module or Why does Perl says 'Undefined subroutine'.

thanks,
katharnakh.

[KevinADC]

hmmm...not sure what the problem is, your code works fine for me. Are you sure the B.pm file you posted is the file your main script is accessing?

[BobUillean]

Where is your B.pm? B isn't a great name for a package - it will clash with the standard 'B' module that ships with Perl. Maybe perl picks up the core B module rather than yours.

I'd recommend a different name.

[KevinADC]

Good point Bob but it's interesting to note it does work for me as-is. ActiveState Perl 5.8.8 which does include perls 'B' module.

[katharnakh]

Hey Bob, Kevin big thanks guys...

I was not aware of B module, which ships with perl distribution. Now i have changed the package name and works fine, and its usage in the other script. Well thats a good point Bob.

@Kevin, I am not using Active perl, im using standard distribution of Perl which my employer providing. Well even i dont know how did it worked for you.

well, thanks again.
cheers,
katharnakh.

[BobUillean]

I'd guess that katharnakh's @INC meant that the core B was 'use'd before the test version.

[KevinADC]

Yes, I guess. I put the A and B modules in the same directory as the script, not sure if the directory the script is in is found first by @INC or if there is in fact any standard order for @INC at all.