Re^5: Use method/function signatures with Perl

[Juerd]

Funny. I thought that I just said that Attribute::Property is an unacceptable solution to me. That means that it doesn't take away the issue.

I'm not disagreeing about that. You said that I indicated something; I cannot recall having indicated that exact thing, and tried to correct.

Let's not make a big deal out of everything. Feel offended if you wish, but please only do so knowing that I didn't mean "flawed" as an absolute condemnation and that no offense was intended. I like Perl for its tolerance towards almost all programming styles, but that doesn't mean I steer clear of discussion.

With OO I'd expect to be able to do something like create a Length module, Length objects can be accessed/set in various units (inches, meters, feet, miles, etc). An external user should have no idea what the internal representation is. How do I do it with lvalues?

In that rather specific case I would not use lvalues, or any setter method, for that matter. I'd be inclined to think of these values as immutable objects, and have something like:

package Length;

sub new {
    my ($class, $value, $unit) = @_;
    # Create $self and store the value in standard form. 
    # In case of length this means converting the length to meters.
}

sub as_km  { shift->{_m} / 1000 }
sub as_hm  { shift->{_m} / 100 }
sub as_dam { shift->{_m} / 10 }
sub as_m   { shift->{_m} }
sub as_dm  { shift->{_m} * 10 }
sub as_cm  { shift->{_m} * 100 }
sub as_mm  { shift->{_m} * 1000 }

# Or, if this were really something I made, just:
sub as {
    my ($self, $unit) = @_;
    # ...
}

But instead of using Length objects, I am much more likely to dictate that every length must be stored in meters, as a number. Possibly with the addition of utility functions to aid in conversion.

And whichever I do, I'll feel free to dislike people who categorically declare that my considered set of choices are flawed.

I'm sorry you make this about people. I wonder, though, how you survive PM if you take offense every time someone disagrees with you on a technical subject. You are of course free to dislike me, or any person. Even though we will probably never meet in person, I regret that you dislike *me* instead of only what I said.