"Michael Lazzaro" <[EMAIL PROTECTED]> wrote: > After thinking about it a little more, I'll set myself on the "yes" > side. And propose either '===' or ':=:' to do it.
Definitely '==='. This is used in various other languages. > > $obj1 eq $obj2; # [1] are their stringifications identical? > > $obj1 == $obj2; # [2] are their numifications identical? > > $obj1 === $obj2; # [3] are they in fact the same object? > > The reason being that you could in fact want to say any of [1], [2], > and [3] as separate, useful concepts. So merely overloading '==' or > 'eq' would not be sufficient, as it would hide the previous, still > useful meanings. There's actually a fourth concept: two (different) objects represent the same value. (Actually, its the generalization of [1] and [2]). Unfortunately, this concept gets fuzzy because there may be multiple equivalence classes that define different values of same-ness for a given pair of objects. As a trivial example, consider the equivalence class of case insensitivity, applied to strings. The current way of defining this is to say: ($a.lc eq $b.lc) # assuming lc is a member, not a sub But this requires us to create two new strings before we can compare them. Whilst there might be optimizations for special cases, the general problem remains: its not nice to define equivalence classes as conversions to strings/numbers. Another way of expressing the above example, is: $a.compare_case_insensitive($b) or compare_case_insensitive($a, $b) This is a general solution, but it seems a bit heavyweight for many/most specific cases. It seems to me that most objects/classes have a default definition of sameness. For this, it'd be nice to use a simple operator (e.g. '==' or 'eq') If I defined my Str $a is CaseInsensitive = "hELLO"; then I would like C< $a eq "Hello" > to DWIM. Can this be applied to other objects? If I have a class named PostalAddress, then I'd expect to compare them as addresses, not as strings. Instead of $a.canonical_value eq $b.canonical_value. I just want to use C<eq> (or, if you insist, a new operator that currently has no name). Sameness is probably a more common operator then identical-ness (I use the latter frequently: but I write a lot of code for testing and debugging -- its my job). So perhaps the C<===> operator could be used for comparison under the default equivalence-class of the operands. I'd find it unintuitive, but I'm could get used to it. Dave.
