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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



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:
http://d.puremagic.com/issues/show_bug.cgi?id=3492




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
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3492


Walter Bright <bugzilla digitalmars.com> changed:

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


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Jan 23 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

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



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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Feb 26 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
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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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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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Feb 26 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
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Jonathan M Davis <jmdavisProg gmx.com> changed:

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



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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Feb 26 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
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timon.gehr gmx.ch changed:

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





 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.

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Feb 27 2012
prev sibling parent d-bugmail puremagic.com writes:
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10:48:35 PST ---

because then every subsequent definition of the nested function conflicts with


the rest.

You can make test() a template function.

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