Seems like it'd be less work to write: 
sub new
{
    croak "new() called as a function, not a method\n" unless @_;
    bless {}, shift;
}

[download]

As dragonchild already pointed out, this would not handle Foo::new({}), nor would it handle Foo::new("Data::Dumper"). Both are things are equally as stupid for a user to do, but a new user may not realize the method/function difference, the real question is whether that is my reponsibility or not.

If you really want to be paranoid, though, you should make something similar a precondition of all of your methods.

I assume you mean to check $self, that is true, but even I think that would a little much.

Also, you ought to call isa() directly, not through UNIVERSAL::, in case someone overrides it.

That too would not work for Foo::new({}) or other such insanity.

I am really just trying to find something in between totally over-the-top paranoid, and you-break-it-you-buy-it-an-I-dont-care. And I am still looking as I think the example I gave above it probably too much.

-stvn

In reply to Re^4: Is "ref($class) || $class" a bad thing? by stvn
in thread Is "ref($class) || $class" a bad thing? by stvn

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