> This has come up before and the discussion > always semi-warnocks, but
Yeah... > 1) Have a version of the binary vtable > methods that create the destination PMC > 2) Make a universal assignment PMC that > takes on the characteristics > of the RHS of the assignment > 3) Have a "this PMC intentionally left blank" > flag to mark blank PMCs > and have vtable methods check that first > #1 doubles the number of vtable entries. Ick. > #2 has the most overhead > #3 leaves it to the vtable methods to check, > which is error prone. Well, as I was saying last summer, #1 is really what the add instruction should have done in the first place, as that would make it behave the same way as it does for ints and floats (replacing the value, not altering the current one), and it is what most high level languages expect, anyway. However, my argument was mostly about the former (that opcode name and IMCC syntax should differentiate between the 2 types of behavior) rather than the latter (that there should be a non-destructive version of PMC add). The Right Thing to do would be to rename the current add op to "add_destructive" or something, and call the new one just "add", acting like add for ints and floats. The imcc "a = b + c" opererator would use the non-destructive version. But judging by the way I was pretty much ignored the first time, and that Dan's already using Parrot at work, and nobody wants to re-write the code they started working on last week, I don't expect that to actually happen. But it would be the Right Thing. whether or not any opcode renaming is done, I'd say that adding the non-destructive ops is probably the best thing to do, as HLLs are going to want them anyway. It certainly makes the compiler's job a lot easier, and would lead to much cleaner output. Otherwise these operations would have to be implemented as methods (or something) in any case where the compiler doesn't know *exactly* what kind of object an arithmetic operation will result in. __________________________________ Do you Yahoo!? Yahoo! Finance Tax Center - File online. File on time. http://taxes.yahoo.com/filing.html
