Bug 4530 – Tidier function types

This is a valid D2 code (dmd 2.047): import std.stdio; void main() { string a(); } Allowing/keeping ugly and error-prone function literals in D2 is bad. It's better for D2 to keep/allow only _one_ standard, clean and readable syntax for functions pointers (and one for delegates, if necessary). Keeping C function pointer syntax or something similar in D2 causes troubles.

(In reply to comment #0) > Allowing/keeping ugly and error-prone function literals in D2 is bad. It's > better for D2 to keep/allow only _one_ standard, clean and readable syntax for > functions pointers (and one for delegates, if necessary). Keeping C function > pointer syntax or something similar in D2 causes troubles. 'a' is not a function literal... it's a declaration of a nested function. The C syntax for a function pointer would be: string (*a)(); which I think is pretty unambiguous.

(In reply to comment #1) > string (*a)(); > > which I think is pretty unambiguous. It isn't. Could be a function called string, which is being called with argument (*a), and the function returned from that call then called with an empty argument list. D grammar aims to be unambiguous. Removing C-style casts has already been a step in the right direction. Removing C-style function pointer declarations would be another.

Or a static opCall on the string type. Or an extension method opCall(string b, int a){...}

But as far as the parser is concerned, that's still a function call. It's the semantic analyser that identifies whether string is an actual function, a function pointer or delegate, a type on which a static opCall is defined, an object of a type that has an opCall, or whatever. A function pointer declaration, on the other hand, is a syntactical form distinct from all of these.

See also enhancement request 4580

In the original comment, there is no 'ugly and error-prone function literal'. There is a nested function declaration with no body. import std.stdio; void main() { string a(); pragma(msg, typeof(&a)); } Prints: string delegate()