digitalmars.D.bugs - [Issue 5893] New: Allow simple aliases for operator overloading
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http://d.puremagic.com/issues/show_bug.cgi?id=5893
Summary: Allow simple aliases for operator overloading
Product: D
Version: D2
Platform: All
OS/Version: All
Status: NEW
Severity: enhancement
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: schveiguy yahoo.com
13:04:35 PDT ---
If you wish to use virtual operators in D classes, the current thinking is you
would wrap a virtual function with a template function that handles the
operator. This means you have to implement a template function, taking care to
use the same arguments that the other function will require, and using the
proper return type as well.
I thought of an alternative way to do this that makes wrapping virtual
functions super-easy. However, the compiler rejects it (for a strange reason).
class C
{
void concatAssign(C other) { }
void concatAssign(int other) { } // to demonstrate overloading
template opOpAssign(string s) if (s == "~=") // line 6
{ alias concatAssign opOpAssign; }
}
void main()
{
auto c = new C;
c.opOpAssign!"~="(c); // works
c.opOpAssign!"~="(1); // works
c ~= 1; // line 15
}
testaliasvirt.d(6): Error: template testaliasvirt.C.opOpAssign(string s) if (s
== "~=") is not a function template
testaliasvirt.d(15): Error: cannot append type int to type testaliasvirt.C
I think the compiler should accept this code. In fact, I thought the compiler
just rewrote ~= to .opOpAssign!"~=". The error message seems to suggest it
does some unnecessary checking to make sure it's a function template.
If it did work, this method provides not only a very efficient and backwards
compatible way to do operators (no wrapper code is generated/called, no relying
on inlining to make sure performance isn't hurt), but one could easily create a
single mixin that forwarded all operators to the old style operators (if you
didn't want to do it manually like I have). You don't even need to deal with
forwarding parameters (the biggest pain of auto-wrapping functions)!
I can see this being of use for opDispatch as well.
Note that bug 4182 would have to be fixed for true backward compatibility (i.e.
forwarding covariance with the virtual operators). But that technically is a
separate issue, not a blocker.
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Apr 26 2011
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=5893
Andrej Mitrovic <andrej.mitrovich gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |andrej.mitrovich gmail.com
18:19:18 PST ---
Hows this for a workaround:
import std.traits;
class C
{
void concatAssign(C other) { }
void concatAssign(int other) { }
auto ref opOpAssign(string s, T)(T t) if (s == "~")
{
static if (is(ReturnType!concatAssign == void))
concatAssign(t);
else
return concatAssign(t);
}
}
void main()
{
auto c = new C;
c.opOpAssign!"~"(c); // works
c.opOpAssign!"~"(1); // works
c ~= 1; // works
}
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Jan 21 2012
http://d.puremagic.com/issues/show_bug.cgi?id=5893
timon.gehr gmx.ch changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |timon.gehr gmx.ch
1. The static if in the function body is not required. You can return a void
expression from a void function.
2. Here is what still does not work:
class C{
void concatAssign(C other) { }
void concatAssign(short other) { }
void concatAssign(short[] other) { }
auto ref opOpAssign(string s, T)(T t) if (s == "~"){
return concatAssign(t);
}
}
void main()
{
auto c = new C;
c.opOpAssign!"~"(c); // works
c.opOpAssign!"~"(1); // no go
c ~= 1; // no go
c ~= [1,2,3]; // no go
// (compare to)
short[] s;
s ~= 1; // works
s ~= [1,2,3]; // works
}
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Jan 21 2012
http://d.puremagic.com/issues/show_bug.cgi?id=5893
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |pull
https://github.com/D-Programming-Language/dmd/pull/989
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Jun 07 2012
http://d.puremagic.com/issues/show_bug.cgi?id=5893 Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/8bc59cfe8e6896435f20ce1e9bdcc226942f59a8 fix Issue 5893 - Allow simple aliases for operator overloading https://github.com/D-Programming-Language/dmd/commit/2888ec45218e2e49048e9f96be2fa0481dc00e31 Issue 5893 - Allow simple aliases for operator overloading -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Nov 22 2012
http://d.puremagic.com/issues/show_bug.cgi?id=5893 13:27:26 PST ---Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/8bc59cfe8e6896435f20ce1e9bdcc226942f59a8 fix Issue 5893 - Allow simple aliases for operator overloading https://github.com/D-Programming-Language/dmd/commit/2888ec45218e2e49048e9f96be2fa0481dc00e31 Issue 5893 - Allow simple aliases for operator overloadingThe OP sample still fails. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Feb 05 2013
http://d.puremagic.com/issues/show_bug.cgi?id=5893
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
Commits pushed to master at https://github.com/D-Programming-Language/dmd
https://github.com/D-Programming-Language/dmd/commit/8bc59cfe8e6896435f20ce1e9bdcc226942f59a8
fix Issue 5893 - Allow simple aliases for operator overloading
https://github.com/D-Programming-Language/dmd/commit/2888ec45218e2e49048e9f96be2fa0481dc00e31
Issue 5893 - Allow simple aliases for operator overloading
The OP sample still fails.
The OP sample cannot compile, because ConcatAssignExp will try to instantiate
opOpAssign!("~"). Correct sample code is:
class C
{
void concatAssign(C other) { }
void concatAssign(int other) { } // to demonstrate overloading
template opOpAssign(string s) if (s == "~") // FIXED
{ alias concatAssign opOpAssign; }
}
void main()
{
auto c = new C;
c.opOpAssign!"~"(c); // works
c.opOpAssign!"~"(1); // works
c ~= 1; // line 15
}
So, this bug is already fixed.
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Feb 05 2013
http://d.puremagic.com/issues/show_bug.cgi?id=5893
17:33:07 PST ---
template opOpAssign(string s) if (s == "~") // FIXED
This is actually worthy of an enhancement. If "~=" is found in opOpAssign the
compiler should inform the user to use "~" instead. The same goes for +=, etc.
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Feb 05 2013
http://d.puremagic.com/issues/show_bug.cgi?id=5893 08:55:06 PST ---In my defense, I believe that originally it DID work the way I specified, whether it be by design or by accident ;) -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------The OP sample still fails.The OP sample cannot compile, because ConcatAssignExp will try to instantiate opOpAssign!("~").
Feb 06 2013