@ISA won't help for function calls, only for method calls. You can call functions in other packages by qualifying them, or by switching package temporarily; you could also export a function in a package and import it into your main script (see Exporter). @ISA only works for method lookup, so you need an object.

Having the *.pm files myblib and vlog 

package myblib;
sub foo { print +(caller(0))[3],"(@_)\n" }
1;

[download]
package vlog;
use myblib;
sub bar { print +(caller(0))[3],"(@_)\n" }
1;

[download]
here are various flavours of calls: 
# line 1 gen.pl
use vlog;
myblib::foo(1);
myblib->foo(2);

# foo();        # this would die - no foo() in main::
# bar();        # as would this

package myblib; # temporarily switch package
foo(3);
package main;   # switch back

@ISA = qw(myblib);
$a = bless do { \ my $x }, 'main';

$a->foo(4);      # method lookup finds foo() in myblib::

# shoehorn the foo() function into main:: - that's roughly
# what Exporter and 'use myblib qw(foo)' do

*foo = *myblib::foo;

foo(5);          # now found in main::
$a->foo(6);
__END__
myblib::foo(1)
myblib::foo(myblib 2)
myblib::foo(3)
myblib::foo(main=SCALAR(0x818c688) 4)
myblib::foo(5)
myblib::foo(main=SCALAR(0x818c688) 6)

[download]

--shmem 

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

In reply to Re: Calling subroutine from other module by shmem
in thread Calling subroutine from other module by isha

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