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digitalmars.D.bugs - [Issue 4530] New: Tidier function types

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4530

           Summary: Tidier function types
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: bearophile_hugs eml.cc



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.

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Jul 28 2010
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4530


Justin Spahr-Summers <Justin.SpahrSummers gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Justin.SpahrSummers gmail.c
                   |                            |om



2010-07-28 18:17:15 CDT ---


 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.

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Jul 28 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4530


Stewart Gordon <smjg iname.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |smjg iname.com





 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.

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Jul 28 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4530




09:21:49 PDT ---
Or a static opCall on the string type.
Or an extension method opCall(string b, int a){...}

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Jul 29 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4530




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.

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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See also enhancement request 4580

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Aug 03 2010
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=4530


yebblies <yebblies gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |yebblies gmail.com
         Resolution|                            |INVALID



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()

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Jun 15 2011