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digitalmars.D.bugs - [Issue 4675] New: Eponymous Template should hide internal names

reply d-bugmail puremagic.com writes:
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           Summary: Eponymous Template should hide internal names
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: andrej.mitrovich gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich gmail.com> 2010-08-18
13:19:16 PDT ---
Code:

import std.stdio;
void main()
{

}

template isNumeric(T)
{
    enum bool test1 = is(T : long);     // should be hidden
    enum bool test2 = is(T : real);     // should be hidden
    enum bool isNumeric = test1 || test2;
}

unittest
{
    static assert(isNumeric!(int).test1);   // should be an error
    writeln(isNumeric!(int).test1);         // should be an error, but writes
true
    writeln(isNumeric!(int).test2);         // should be an error, but writes
true
}

According to TDPL, calling isNumeric!(T) is rewritten by the compiler to
isNumeric!(T).isNumeric, therefore hiding access to any other names.

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next sibling parent d-bugmail puremagic.com writes:
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Torarin <torarin gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |torarin gmail.com


--- Comment #1 from Torarin <torarin gmail.com> 2010-08-20 17:26:26 PDT ---
I ran into trouble with this example as well, but this time because what should
work, doesn't:

import std.stdio;

template isNumeric(T)
{
  enum bool test1 = is(T : long);
  enum bool test2 = is(T : real);
  enum bool isNumeric = test1 || test2;
}

void main()
{
  bool a = isNumeric!int;
}


Fails with:
test.d(12): Error: expression isNumeric!(int) is void and has no value.

I was surprised to find that the language reference actually contradicts TDPL
here:

"Implicit Template Properties
If a template has exactly one member in it, and the name of that member is the
same as the template name, that member is assumed to be referred to in a
template instantiation."


(In reply to comment #0)
 According to TDPL, calling isNumeric!(T) is rewritten by the compiler to
 isNumeric!(T).isNumeric, therefore hiding access to any other names.
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--- Comment #2 from Andrej Mitrovic <andrej.mitrovich gmail.com> 2010-08-20
17:35:05 PDT ---
There are more cases of contradiction, but I think this has to do with some of
the spec not being updated. In other cases some features are simply not yet
implemented.. My guess is that this feature should be implemented like it
states in TDPL.

Otherwise for any non-trivial templates you would have to write code like:

isNumeric!(int).isNumeric

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--- Comment #3 from Torarin <torarin gmail.com> 2010-08-20 17:54:25 PDT ---
Yes. std.traits deals with it by doing

private template hasRawAliasing(T...)
{
    enum hasRawAliasing
        = hasRawPointerImpl!(RepresentationTypeTuple!(T)).result;
}

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bearophile_hugs eml.cc changed:

           What    |Removed                     |Added
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                 CC|                            |bearophile_hugs eml.cc


--- Comment #4 from bearophile_hugs eml.cc 2010-08-27 16:26:55 PDT ---
Time ago some people have proposed to allow "private" for that purpose:

template isNumeric(T) {
    private enum bool test1 = is(T : long);
    private enum bool test2 = is(T : real);
    enum bool isNumeric = test1 || test2;
}


This is good because the person that reads the code doesn't need to remember
the rule that test1 and test2 become invisible if isNumeric is defined inside
isNumeric(). So I think this is a more tidy solution to the problem.

On the other hand you want all names to be private but the one that is
eponymous, so the solution in TDPL is shorter (and probably acceptable still).

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Kenji Hara <k.hara.pg gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


--- Comment #5 from Kenji Hara <k.hara.pg gmail.com> 2011-12-31 05:39:13 PST ---
https://github.com/D-Programming-Language/dmd/pull/590

Eponymous member always hides other members (do not consider access
attributes).

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Walter Bright <bugzilla digitalmars.com> changed:

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


--- Comment #6 from Walter Bright <bugzilla digitalmars.com> 2012-01-15
19:17:09 PST ---
https://github.com/D-Programming-Language/dmd/commit/91facb7b443bb61793b045fab9715be633f1aa99

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--- Comment #7 from dawg dawgfoto.de 2012-01-22 01:37:35 PST ---
*** Issue 2640 has been marked as a duplicate of this issue. ***

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Denis <verylonglogin.reg gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |verylonglogin.reg gmail.com


--- Comment #8 from Denis <verylonglogin.reg gmail.com> 2012-01-25 02:06:38 MSK
---
Still doesn't work in most real-life (Phobos) cases. Filled Issue 7363.

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