Using the Variant (Setting it's memory location)

[Pedro Lacerda]

Umm, sounds nice. If you want to store a long into buffer, you can cast the
desired position as long* and assign the value. The following is adapted
from std.outbuffer, that is another option.

    ubyte buffer[];
    size_t offset;

    ulong a = 1;
    byte b = 2;

    // allocate space for ulong e byte
    buffer.length = a.sizeof + b.sizeof;

    *cast(ulong *)&buffer[offset] = a; // store value
    offset += a.sizeof;                // increment offset

    *cast(byte *)&buffer[offset] = b;
    offset += b.sizeof;


Pedro Lacerda



2012/2/8 Era Scarecrow <rtcvb32 at yahoo.com>

> On Tuesday, 7 February 2012 at 17:51:42 UTC, Pedro Lacerda wrote:
>
>> You can roll your own tagged union instead. The S struct can store long
>> and
>> byte[], S.ptr is a pointer to the data.
>>
>
>
> Yep, a bit like my code, except with switch cases covering all major
> types; That and trying to do comparison and setting functions, which seems
> a bit much. Testing it using templates and testing all the types seems like
> a nightmare. I've decided I need to pass it a ubyte array so I could do
> bounds checking before binding the memory to the union. One fewer things to
> worry about.
>
> Let's see... not that I expect you to use this, but I sorta have this as
> my enum set for types.
>
>
> enum ValueType {
>        raw             = 0x00000000,           ///default upon unknown
>        mask_types      = 0xfff00000,           ///Upper 4k defines general
> types, or 12 flag types
>        mask_size       = 0x000fffff,           ///lower gives 1Million for
> size.
>
>        i_types         = 0x00100000,           ///integars types
>        i_8 = i_types + byte.sizeof,
>        i_16 = i_types + short.sizeof,
>        i_32 = i_types + int.sizeof,
>        i_64 = i_types + long.sizeof,
>
>        u_types         = 0x00200000,           ///unsigned numbers
>        u_8 = u_types + ubyte.sizeof,
>        u_16 = u_types + ushort.sizeof,
>        u_32 = u_types + uint.sizeof,
>        u_64 = u_types + ulong.sizeof,
>
>        floating_types  = 0x00400000,
>        float_32 = floating_types + float.sizeof, fl = float_32,
>        double_64 = floating_types + double.sizeof, doub = double_64,
>
>
>        flags_types     = 0x00800000,
>        flags_8 = flags_types + ubyte.sizeof,
>        flags_16 = flags_types + ushort.sizeof,
>        flags_32 = flags_types + uint.sizeof,
>        flags_64 = flags_types + ulong.sizeof,
>
>        ranged_types = 0x01000000,
>        ranged_8 = ranged_types + ubyte.sizeof,
>        ranged_16 = ranged_types + ushort.sizeof,
>        ranged_32 = ranged_types + uint.sizeof,
>        ranged_64 = ranged_types + ulong.sizeof,
>
>        voidp = 0x02000000, pointer_types = voidp,      ///pointers
>        i_8p,           u_8p,
>        i_16p,          u_16p,
>        i_32p,          u_32p,
>        i_64p,          u_64p,
>        float_32p,      double_64p,
>
>        var_str         = 0x04000000,
>        fixed_str       = 0x08000000,
>        var_ustr        = 0x10000000,
>        fixed_ustr      = 0x20000000
> }
>
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