OO Slip-up Preventor

Stops fools from doing $obj = Class::new(...) when they should be doing $obj = new Class (...) or $obj = Class->new(...), or even $obj = Class::new(Class, ...).

This works in all but pathological cases such as:

my $foo = Class->new( this => 2, that => 3 );
my $bar = Class::new( $foo => 4, that => 5 );
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where the first argument to the constructor (after the class name) is an object which isa-resolves to the package name.

package Class;

sub new {
  unshift @_, __PACKAGE__
    unless $_[0]->isa(__PACKAGE__);
  # rest of code...
}
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(tye)Re: OO Slip-up Preventor by tye (Sage) on Jan 18, 2001 at 20:05 UTC
Rather than `$_[0]->isa` I'd write `UNIVERSAL::isa($_[0],__PACKAGE__)` because if your first argument is "" or "\t", just to give two examples, then your code dies. - tye (but my friends call me "Tye")	[reply] [d/l] [select]
Re: (tye)Re: OO Slip-up Preventor by japhy (Canon) on Jan 18, 2001 at 20:34 UTC
I find that silly. Why does Perl allow `"what a croc"->isa('foo')`, but doesn't allow `" what a croc"->isa('foo')`? I find that highly shifty. (Harumph.) `japhy` -- Perl and Regex Hacker	[reply]
Re: OO Slip-up Preventor by Anonymous Monk on May 28, 2002 at 23:26 UTC
Stops fools This is nit-picking, but I'd say it does the opposite; it lets fools continue to be fools. Also, `Class::new([]);` makes it break. Another good reason to use `UNIVERSAL::isa($_[0], __PACKAGE__)`. Cheers, -Anomo	[reply] [d/l] [select]