Your code doesn't make any sense. Here's what I assume you are trying to do (which actually works when you run it, a characteristic that is useful for trying things out): 
package Classes::SomeParent;
1;
package Classes::SomeChild;
our @ISA=("Classes::SomeParent");
package main;

my $class = 'Classes::SomeChild;
my $obj = {};
bless $obj, 'Classes::SomeChild';
if ($obj->isa('Classes::SomeParent')) {
    print "Isa";
} else {
    print "Nota";
}

[download]
prints "Isa". Likewise if you give it $class instead of $obj. My advice would be to directly inspect the @ISA of the relevant class in the debugger at that point to make sure it's correct. Of course, I am assuming that SomeChild is actually supposed to be a child of SomeParent, which you don't state.

(NB: The "is_tainted" function in perlsec isn't doing what I expect it to -- to wit, 

print "Object is ". (is_tainted($obj) ? "not " : "") . "tainted";

[download]
always claims that $obj is tainted.)

Post some more, and maybe we can figure it out.
---
"I hate it when I think myself into a corner."
Matt Mitchell

In reply to Re: isa() and taint checking by antifun
in thread isa() and taint checking by webby

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