Template method and type resolution of return type

[matovitch via Digitalmars-d-learn]

On Saturday, 19 April 2014 at 18:46:28 UTC, matovitch wrote:
> On Saturday, 19 April 2014 at 17:49:54 UTC, bearophile wrote:
>> matovitch:
>>
>>> struct Test
>>> {
>>> 	immutable (ubyte)[] data;
>>>
>>> 	T get(T)()
>>> 	{
>>> 		return *(cast(T*)(&(data[0])));
>>> 	}
>>
>> It's better to return const/immutable data. Otherwise the 
>> program gives undefined results. In alternative use mutable 
>> ubytes for data.
>>
>> Also &data[0] is probably data.ptr.
>
> I did'nt know that one.
>
>>
>>
>>> This won't compile :
>>>
>>> import std.stdio;
>>>
>>> void main()
>>> {
>>> 	Test t;
>>> 	t.data = [152, 32, 64, 28, 95];
>>> 	float b = t.get;
>>> 	writefln("%s", b);
>>
>> D doesn't perform inference on the return type.
>
> I see. But why ?
>
> It's seems it exits a workaround overloading cast operators in 
> c++ :
>     
> http://programmaticallyspeaking.blogspot.se/2012/09/infer-return-type-for-templated.html
>
> However I think it would only work with opImplicitCast in D. 
> The code given in vibe.d doc could became :
>
> void manipulateJson(Json j)
> {
> 	j = Json.emptyObject;
> 	j.name = "Example";
> 	j.id = 1;
>
> 	// retrieving the values is done using get()
> 	assert(j["name"] == "Example");
> 	assert(j["id"] == 1);
>
> 	// print out as JSON: {"name": "Example", "id": 1}
> 	writefln("JSON: %s", j.toString());
> }
>
>
> ps : Thank you for all your great examples on Rosetta code (or 
> the last one about the rubik's cube).

Or even :

void manipulateJson(Json j)
{
  	j = Json.emptyObject;
  	j.name = "Example";
  	j.id = 1;

  	assert(j.name == "Example");
  	assert(j.id == 1);

  	// print out as JSON: {"name": "Example", "id": 1}
  	writefln("JSON: %s", j.toString());
}

Or at least this will work :

void manipulateJson(Json j)
{
  	j = Json.emptyObject;
  	j.name = "Example";
  	j.id = 1;

  	string s = j.name;
         assert(s == "Example");


  	// print out as JSON: {"name": "Example", "id": 1}
  	writefln("JSON: %s", j.toString());
}

Ok I stop fooding.