Em Ter, 2009-03-31 às 22:54 -0700, Jon Lang escreveu: > Yes, I know that there is no S08. I'm working on writing one, and I'd > like some feedback to help me do so.
++ > My draft is going to be about Signatures and Captures. Thus, my questions: > Invocants: The concept of "invocant" only exists in terms of syntax now. In runtime the invocant is simply the first positional argument. This simplifies things a lot. > * Is it illegal to specify an invocant in a sub, or is it merely > nonsensical? There's nothing wrong about it. In fact, every time you do "my method" or "our method", you end up with a sub that has an invocant in its signature. > silently treat the invocant as the first positional parameter? Yes, that is basically the major side-effect on the latest capture change. As I said before, the invocant only exists in terms of syntax, it doesn't exist in terms of runtime. > * Likewise, if I interpolate a signature with an invocant into another > signature (somewhere other than at the start), is this an error, or > will the invocant be silently converted into an ordinary positional > parameter? What does "interpolate a signature" mean? But anyway, the invocant is the first positional argument, period. > * What types are you allowed to assign to an invocant? It's just a positional argument. But I suppose that on method declarations, the type of the invocant is ::?CLASS. (Although there is some debate if it's going to make some declarations too narrow unintentionally. > * Does anyone object to roles having an invocant, and that invocant > referring to the class that is doing the role? You mean methods declared in a role? Yes, they have an invocant, but the invocant type in the signature could be just the role, I guess... > * Why are we using ";;" to denote the end of a multi function's > longname? Because a capture may have more than one dimension, which would be delimited by ";". > * Can any required parameter be part of the longname, or are only > positional parameters allowed? (I'm expecting the latter; but I'd > like confirmation.) I suspect you meant "named parameter" in place of "required parameter". For Perl 6.0.0, it is accepted that named parameters don't take part in multi dispatch. > * Are placeholder parameters ever considered to be part of a > function's longname? (I'm expecting that they aren't: if you want a > longname, you ought to specify it in a formal signature.) placeholder variables are just a simplified way of writing a signature, after they are compiled, the routine has a regular signature, which means that it should work as if the signature was explicit. > * Must required named parameters be defined before optional named > parameters are, or are we allowed to interleave the two? named parameters order are, most of the time, irrelevant. But you can have the same named parameter twice, iirc. So, I don't think you need to put mandatory named parameters before the regular ones... > * does the use of placeholder parameters interfere with the use of the > slurpy parameters normally provided by the default signature (i.e., > *...@_ and *%_)? I'm guessing not. Yes, it does. The default signature is the *default*. Having placeholder parameters imply defining a signature, one could argue that *...@_ and *%_ are still part of that generated signature, but @_ certainly won't contain the values that were in the placeholder parameters. daniel
