Re: Simple OO Question

That's not what I get:

>perl -w tmp.pl
Use of uninitialized value in print at tmp.pl line 25.
me
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That is because in ->Show_Me, you're calling _Print_me while you should be calling ->_Print_Me instead:

sub Show_Me {
    my ($self) = @_;

    return $self->_Print_Me(); # <--
}
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Comment on Re: Simple OO Question Select or Download Code

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Re^2: Simple OO Question by DStaal (Chaplain) on Sep 16, 2010 at 13:02 UTC
As an expansion: `_Print_Me()` is expecting an argument (a reference to a hash), which it puts in `$self`. It then prints the hash element `user` out of that argument. In your version of `Show_Me`, you don't pass it that expected argument. There are two ways to do so in this case: Using standard function notation (`_Print_Me($self)`) or using object notation, which implies the object itself as the first argument. (`$self->_Print_Me()`)	[reply] [d/l] [select]
Re^3: Simple OO Question by dsheroh (Monsignor) on Sep 16, 2010 at 13:21 UTC
As a further expansion: The difference between `_Print_Me($self)` and `$self->_Print_Me` is that `_Print_Me($self)` will always use the current package's `_Print_Me`, while `$self->_Print_Me` will find the appropriate `_Print_Me` for the package (class) that `$self` is blessed into. As a general rule, you'll want to use `_Print_Me($self)` when you want to use one specific implementation, no matter what, and use `$self->_Print_Me` when you want to allow for polymorphism (which should be almost always, since you never know when `$self` might belong to a subclass which has overridden `_Print_Me`).	[reply] [d/l] [select]