Re: Getting the parameters of a struct/class constructor
On 1/24/13, Andrej Mitrovic wrote:
> On 1/24/13, Joseph Rushton Wakeling wrote:
>> ParameterTypeTuple!(A.this)
>
> Use ParameterTypeTuple!(A.__ctor)
>
If you have multiple constructors you can pick the parameters with a
helper template:
import std.traits, std.string;
struct A
{
this(int a, double b)
{
}
this(float y)
{
}
}
template PickCtorParams(Type, size_t index)
{
enum ctorLen = __traits(getOverloads, Type, "__ctor").length;
static if (index < ctorLen)
{
alias ParameterTypeTuple!(__traits(getOverloads, A,
"__ctor")[index]) PickCtorParams;
}
else
{
static assert(0,
format("index %s exceeds %s ctors for type %s", index,
ctorLen, Type.stringof));
}
}
void main()
{
pragma(msg, PickCtorParams!(A, 0)); // (int, double)
pragma(msg, PickCtorParams!(A, 1)); // (float)
pragma(msg, PickCtorParams!(A, 2)); // out of bounds
}
Re: Getting the parameters of a struct/class constructor
On 01/24/2013 06:14 PM, Andrej Mitrovic wrote: On 1/24/13, Joseph Rushton Wakeling wrote: ParameterTypeTuple!(A.this) Use ParameterTypeTuple!(A.__ctor) Brilliant. Thanks very much. :-)
Re: Getting the parameters of a struct/class constructor
There may be more than one "this", so you'll have to specify the
args for each specific constructor manually.
Disclaimer: Someone else may have a better solution as I'm not
that much of an expert in this area.
This sample may point you in the right direction ...
import std.typetuple;
struct X
{
alias TypeTuple!(int, double) CONSTUCT1;
alias TypeTuple!(int, double, string) CONSTUCT2;
this( CONSTUCT1 args )
{
alias args[0] a_int;
alias args[0] a_double;
_a = a_int;
_b = b_double;
}
this( CONSTUCT2[0] a_int, CONSTUCT2[1] b_double, CONSTUCT2[2]
c_string )
{
_a = a_int;
_b = b_double;
writeln(c_string);
}
int _a;
double _b;
}
void foo(X.CONSTUCT1[0] a, X.CONSTUCT1[1] b )
{
...
}
void bar(X.CONSTUCT2 args )
{
alias args[0] a_int;
alias args[1] a_double;
alias args[2] a_string;
...
}
Hope this helps.
--rt
Re: Getting the parameters of a struct/class constructor
You can use "magic" functions __ctor and __dtor which actually serve as constructor and destructor implementations behind the scene. Example and proof-of-concept: http://dpaste.1azy.net/fd924332 Have no idea if it is explicitly defined by spec somewhere though.
Re: Getting the parameters of a struct/class constructor
On Thursday, 24 January 2013 at 18:41:31 UTC, mist wrote: You can use "magic" functions __ctor and __dtor which actually serve as constructor and destructor implementations behind the scene. Example and proof-of-concept: http://dpaste.1azy.net/fd924332 Have no idea if it is explicitly defined by spec somewhere though. If you have more than one ctor it seems to take the first one http://dpaste.1azy.net/b994fdf3 I don't know if you will able to rely on the order unless it's a part of the spec. --rt
Re: Getting the parameters of a struct/class constructor
On Thu, Jan 24, 2013 at 10:34 PM, Rob T wrote: > On Thursday, 24 January 2013 at 18:41:31 UTC, mist wrote: >> >> You can use "magic" functions __ctor and __dtor which actually serve as >> constructor and destructor implementations behind the scene. >> >> Example and proof-of-concept: http://dpaste.1azy.net/fd924332 >> >> Have no idea if it is explicitly defined by spec somewhere though. > > > If you have more than one ctor it seems to take the first one > > http://dpaste.1azy.net/b994fdf3 > > I don't know if you will able to rely on the order unless it's a part of the > spec. IIRC, you can use __traits(getOverloads, mytype.__ctor) to get all constructor overloads. See: http://dlang.org/traits.html#getOverloads I used this in conjunction with __traits(getMember, ...) to get the entire list of member, overloads included.
Re: Getting the parameters of a struct/class constructor
On 1/24/13, Philippe Sigaud wrote:
> IIRC, you can use __traits(getOverloads, mytype.__ctor) to get all
> constructor overloads.
> See:
> http://dlang.org/traits.html#getOverloads
>
> I used this in conjunction with __traits(getMember, ...) to get the
> entire list of member, overloads included.
>
I don't understand why, but it seems DForum doesn't show up any of my
posts. I've posted this as my second reply (hope this makes it):
If you have multiple constructors you can pick the parameters with a
helper template:
import std.traits, std.string;
struct A
{
this(int a, double b)
{
}
this(float y)
{
}
}
template PickCtorParams(Type, size_t index)
{
enum ctorLen = __traits(getOverloads, Type, "__ctor").length;
static if (index < ctorLen)
{
alias ParameterTypeTuple!(__traits(getOverloads, A,
"__ctor")[index]) PickCtorParams;
}
else
{
static assert(0,
format("index %s exceeds %s ctors for type %s", index,
ctorLen, Type.stringof));
}
}
void main()
{
pragma(msg, PickCtorParams!(A, 0)); // (int, double)
pragma(msg, PickCtorParams!(A, 1)); // (float)
pragma(msg, PickCtorParams!(A, 2)); // out of bounds
}
Re: Getting the parameters of a struct/class constructor
On Thursday, 24 January 2013 at 22:49:33 UTC, Andrej Mitrovic wrote: On 1/24/13, Philippe Sigaud wrote: IIRC, you can use __traits(getOverloads, mytype.__ctor) to get all constructor overloads. See: http://dlang.org/traits.html#getOverloads I used this in conjunction with __traits(getMember, ...) to get the entire list of member, overloads included. I don't understand why, but it seems DForum doesn't show up any of my posts. I've posted this as my second reply (hope this makes it): The thread got split up into two separate threads. Your missing post shows up in the split. I really hate it when it does this. --rt
