Sean O'Rourke wrote: > On Mon, 16 Sep 2002, Leopold Toetsch wrote: > > >>Sean O'Rourke wrote:
>>...it should inherit from some basic_scalar.pmc, that >>implements this for scalars. default.pmc is no more this default scalar >>type, it's a "invalid.pmc". >>Aggregates and Sub's and so on, don't need this function. > Then they shouldn't define _any_ of the add operations. .... and the default.pmc will catch any abuse of adding a "Sub" to an int and throw an exception. > ... IMHO once a class > says how it can be interpreted as e.g. a number, it's eminently reasonable > to default the rest of its numeric operations, and to do widening > conversions to take advantage of implemented ops. Yes of course. What once was in "default.pmc" will be "scalar.pmc", where all scalar like classes can inherit from. > I guess one way to measure which way makes more sense is to put in the new > default.pmc, then see if there end up being any classes inheriting from it > directly, or if everything goes through an intermediate conversion class. As I already stated, we had til now _no_ inheritance from "default.pmc" except for the famous "Subscript on something that's not an aggregate". >>Then they should implement an empty init() function (Currently we don't >>have this case AFAIK). > "Should not!" ;) This is one additional line. Please compare this with 5KB lines I saved in array.pmc. > I'll admit, it took me a little while to figure out why my sub's invoke() > method wasn't getting called, when I added an extra space between the > 'void' and the '*'. invoke() is a poster-child of a method that should > _not_ have a default -- what does it mean to "invoke" an integer? It should throw an exception, which "default.pmc" now does (and in case of invoke already had done) > But I > suspect that there are a lot of operations that can be defined in terms of > others without causing any surprises. The bignum value of something that > knows how to become an int seems perfectly clear to me. Yes, that's the planned inheritance from a scalar.pmc. Summary: default.pmc catches errors, and may provide e.g. ->name or ->type. scalar.pmc will be the default scalar base class. > /s leo
