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digitalmars.D.bugs - [Issue 3492] New: Can't overload nested functions

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3492

           Summary: Can't overload nested functions
           Product: D
           Version: 2.036
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Keywords: spec
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: dsimcha yahoo.com


--- Comment #0 from David Simcha <dsimcha yahoo.com> 2009-11-09 20:35:03 PST ---
Nested functions don't overload like non-nested functions.  If this behavior is
correct, it seems like a fairly arbitrary limitation, but it should be
clarified in the spec.

void main() {
    static void foo(uint a, float b) {}
    static void foo(float a, uint b) {}
}

Error: declaration foo is already defined

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Nov 09 2009
next sibling parent d-bugmail puremagic.com writes:
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--- Comment #1 from github-bugzilla puremagic.com 2012-01-23 01:42:44 PST ---
Commit pushed to
https://github.com/D-Programming-Language/d-programming-language.org

https://github.com/D-Programming-Language/d-programming-language.org/commit/5d98834d711cebd4d218a0580856b84de6dcb10f
fix Issue 3492 - Can't overload nested functions

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Jan 23 2012
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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla digitalmars.com
         Resolution|                            |FIXED


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Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |andrej.mitrovich gmail.com


--- Comment #2 from Andrej Mitrovic <andrej.mitrovich gmail.com> 2012-02-26
14:52:16 PST ---
Nested functions are a great feature, especially when experimenting with code
and when I need to do some quick filtering over e.g. hashes but need to access
some outer state. With nested functions I don't have to use global variables or
use ref parameters (I'm talking about non-static functions).

I've just tried using overloaded functions but failed and found this in
bugzilla. It's not a big issue, I can rename the functions.. but I'd like to
know the rationale for this limitation.

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--- Comment #3 from Walter Bright <bugzilla digitalmars.com> 2012-02-26
22:04:30 PST ---
The reason is straightforward - there's no point to it. Nested functions tend
to be right next to where they are used. They're not off in a separate file.

We shouldn't have features just to have features. They have to have an
identifiable benefit. Overloaded functions introduce complexity both to the
user and the compiler - and there is no clear benefit for nested functions.

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--- Comment #4 from Walter Bright <bugzilla digitalmars.com> 2012-02-26
22:13:25 PST ---
The reason is straightforward - there's no point to it. Nested functions tend
to be right next to where they are used. They're not off in a separate file.

We shouldn't have features just to have features. They have to have an
identifiable benefit. Overloaded functions introduce complexity both to the
user and the compiler - and there is no clear benefit for nested functions.

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Jonathan M Davis <jmdavisProg gmx.com> changed:

           What    |Removed                     |Added
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                 CC|                            |jmdavisProg gmx.com


--- Comment #5 from Jonathan M Davis <jmdavisProg gmx.com> 2012-02-26 22:43:51
PST ---
Really? I'm constantly annoyed by that you can't overload nested functions when
writing unit tests. I frequently need to overload functions in unittest blocks
and have to play games to get around the fact that I can't. The worst is when
you use foreach and TypeTuple. You can't just do something like

foreach(T; TypeTuple!(string, wstring, dstring))
{
    void test(T actual, T expected, ...)
    {
    }

    test(...);
    test(...);
    test(...);
    ...
}

because then every subsequent definition of the nested function conflicts with
the rest. You're force to use string mixins simply to give each overload of the
nested function a unique name. It's an extra complication that really shouldn't
be necessary IMHO.

If anything, I'd argue that the lack of ability to overload nested functions is
an unnecassary inconsistency in the language.

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timon.gehr gmx.ch changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |timon.gehr gmx.ch


--- Comment #6 from timon.gehr gmx.ch 2012-02-27 05:16:59 PST ---
(In reply to comment #4)
 The reason is straightforward - there's no point to it. Nested functions tend
 to be right next to where they are used. They're not off in a separate file.
 
 We shouldn't have features just to have features.
But we do have overloading in the language already. We shouldn't just deny access to existing features. Chances are that a compiler works better if there are no arbitrary inconsistencies (see all the bugs related to parsing storage classes of nested declarations for an example -- just define the language such that reusing parsing procedures is easy.)
 They have to have an identifiable benefit. Overloaded functions introduce
complexity both to the user and the compiler - and there is no clear benefit
for nested functions.
What introduces complexity to the user and the compiler is that the syntax (and, like in this case, even the semantics!) of function local declarations is substantially different from global declarations and declarations inside aggregates. It is not 'turtles all the way down', it is not consistent, and it is not useful. Those are arbitrary limitations. I'd suspect that DMD can even handle correctly most of the function local features that are currently invalid syntax. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
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--- Comment #7 from Walter Bright <bugzilla digitalmars.com> 2012-02-27
10:48:35 PST ---
because then every subsequent definition of the nested function conflicts with
the rest. You can make test() a template function. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 27 2012