My main problem with it is isn't so much the wording, but the fact that it doesn't even say which argument caused the problem.

Sure it does. the message says

Can't call method "isa" on unblessed reference at unblessedWantBetterError.t line 10.

Which tells us that on line 10 some $var is being used as an object in a method call and the content of $var is not actually an object. When we look at line 10 we see 

die "not a foo" unless $obj->isa('foo'); #the error I want

[download]

which tells us that the $var in question is called $obj.

Now presumably you are doing this because later on you have code that does something like 

$obj->do_something($useful);

[download]

But what do you gain? In this situation you would see the same error you are now just on the actual line where the actual code is being used, and not on some validation code.

So IMO you gain nothing but code complexity and you tie the hands of your codes consumers because they can't drop in a different object with a compatible interface. So IOW, you have made your code less usable and robust than more.

---
$world=~s/war/peace/g

In reply to Re^3: How to differentiate hash reference and object reference? by demerphq
in thread How to differentiate hash reference and object reference? by tphyahoo

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