in reply to Re^2: What's happening in this expression? (Updated)
in thread What's happening in this expression?

What about my $a=$x=$y=$z = foo()
$ perl -MO=Deparse,-p -e 'my $a=$x=$y=$z = foo()' (my $a = ($x = ($y = ($z = foo()))));

The comma is left associative and the assignment is right associative. See perlop.

Here my attribute does not propogate like in case of comma.

No, it doesn't "propagate" with the comma either, as I showed.