• d-bugmail puremagic.com (44/44) Mar 29 2014 https://d.puremagic.com/issues/show_bug.cgi?id=12489
• d-bugmail puremagic.com (23/23) Mar 29 2014 https://d.puremagic.com/issues/show_bug.cgi?id=12489
• d-bugmail puremagic.com (12/23) Mar 29 2014 https://d.puremagic.com/issues/show_bug.cgi?id=12489
• d-bugmail puremagic.com (12/14) Mar 30 2014 https://d.puremagic.com/issues/show_bug.cgi?id=12489
• d-bugmail puremagic.com (21/27) Mar 30 2014 https://d.puremagic.com/issues/show_bug.cgi?id=12489

d-bugmail puremagic.com writes:

https://d.puremagic.com/issues/show_bug.cgi?id=12489

           Summary: std.bitmanip byte swapping routines should be
                    partially instantiable
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: andrej.mitrovich gmail.com



12:15:14 CET ---
I've had a use case for generic endianness swapping when reading file headers,
and was going to use attributes. For example:

struct Header
{
     Converter!(littleEndianToNative!ushort)
    ushort reserved1;
}

Unfortunately this doesn't work because you can't partially instantiate
littleEndianToNative:

Error: template instance littleEndianToNative!ushort does not match template
declaration littleEndianToNative(T, uint n)(ubyte[n] val) if
(canSwapEndianness!T && n == T.sizeof)

It would have to be converted to a template, e.g.:

Before:

-----
T littleEndianToNative(T, size_t n)(ubyte[n] val)  safe pure nothrow
-----

After:

-----
template littleEndianToNative(T)
{
    T littleEndianToNative(size_t n)(ubyte[n] val)  safe pure nothrow
    {
        ...
    }
}
-----

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d-bugmail puremagic.com writes:

https://d.puremagic.com/issues/show_bug.cgi?id=12489




12:32:30 CET ---
Here's a somewhat generic wrapper workaround:

-----
template PartialTempl(alias templ, T...)
{
    auto PartialTempl(Args...)(auto ref Args args)
    {
        return templ!T(args);
    }
}
-----

Usable as:


-----
 Converter!(PartialTempl!(littleEndianToNative, ushort))
ushort reserved1;
-----

Of course 'littleEndianToNative' and friends take a ubyte[N], not a ushort, so
in my file loading routine I have to take that into account. But using
attributes is pretty nice.

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d-bugmail puremagic.com writes:

https://d.puremagic.com/issues/show_bug.cgi?id=12489


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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WONTFIX



21:01:05 CET ---

 Here's a somewhat generic wrapper workaround:
 
 -----
 template PartialTempl(alias templ, T...)
 {
     auto PartialTempl(Args...)(auto ref Args args)
     {
         return templ!T(args);
     }
 }
 -----

This solves it for me.

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d-bugmail puremagic.com writes:

https://d.puremagic.com/issues/show_bug.cgi?id=12489


Vladimir Panteleev <thecybershadow gmail.com> changed:

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



14:37:22 EEST ---

      Converter!(littleEndianToNative!ushort)
     ushort reserved1;

I don't know the context, but there's some redundancy here already (ushort is
listed twice). Any reason you can't use ` Converter!littleEndianToNative` ?

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d-bugmail puremagic.com writes:

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14:45:56 CEST ---


      Converter!(littleEndianToNative!ushort)
     ushort reserved1;

 
 I don't know the context, but there's some redundancy here already (ushort is
 listed twice). Any reason you can't use ` Converter!littleEndianToNative` ?

Yeah you're right, I don't need to embed this information. It's really nice
that I can now write:

struct Header
{
     Converter!littleEndianToNative
    {
        ushort reserved1;

        ushort ordnum;

        ushort insnum;

        ushort patnum;

        ushort flags;

        ushort cwtv;

        ushort version_;
    }
}

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