• Manu (14/14) Jan 17 2014 Observing strange behaviour, just want to know if it's correct...
• Jacob Carlborg (5/19) Jan 17 2014 Yeah, that's a really annoying limitation. I'm wonder if there's a
• bearophile (5/7) Jan 17 2014 If the instantiation is automatic, then what's the literal to
• Jacob Carlborg (4/6) Jan 17 2014 Perhaps based on the context, but that might be a bad idea.
• Dicebot (5/10) Jan 17 2014 I think it is impossible in general case:
• Jacob Carlborg (5/9) Jan 17 2014 The compiler would first try the template symbol, if that fails try the
• Manu (3/9) Jan 17 2014 The context gives everything it needs. It's clearly being used to declar...
• bearophile (8/9) Jan 17 2014 I don't think so. If you pass one of those literals to a template
• Jacob Carlborg (5/9) Jan 17 2014 Template name, because you can override that with !() to mean template
• John Colvin (5/25) Jan 17 2014 There's enough subtlety in function identifiers vs function
• monarch_dodra (29/49) Jan 17 2014 The funny part though is that it works if the template is a

Manu <turkeyman gmail.com> writes:

Observing strange behaviour, just want to know if it's correct...

struct VertexBuffer(VertexDataType = void) {}

VertexBuffer x;
  Error: struct VertexBuffer(VertexDataType = void) is used as a type

auto y = VertexBuffer();
  Error: struct VertexBuffer(VertexDataType = void) cannot deduce template
function from argument types !()()

But this works:
VertexBuffer!() z;


Why should I need to supply an empty argument list? This defeats the
purpose of the default arg, and obscures my code in the common case.

Untyped vertex buffers are the default, and it would be nice to be able to
declare them trivially.

Also, those error messages are quite unhelpful.

Jacob Carlborg <doob me.com> writes:

On 2014-01-17 13:18, Manu wrote:
 Observing strange behaviour, just want to know if it's correct...

 struct VertexBuffer(VertexDataType = void) {}

 VertexBuffer x;
    Error: struct VertexBuffer(VertexDataType = void) is used as a type

 auto y = VertexBuffer();
    Error: struct VertexBuffer(VertexDataType = void) cannot deduce
 template function from argument types !()()

 But this works:
 VertexBuffer!() z;


 Why should I need to supply an empty argument list? This defeats the
 purpose of the default arg, and obscures my code in the common case.

 Untyped vertex buffers are the default, and it would be nice to be able
 to declare them trivially.

 Also, those error messages are quite unhelpful.

Yeah, that's a really annoying limitation. I'm wonder if there's a 
bugzilla entry for it.

-- 
/Jacob Carlborg

"bearophile" <bearophileHUGS lycos.com> writes:

Jacob Carlborg:

 Yeah, that's a really annoying limitation. I'm wonder if 
 there's a bugzilla entry for it.

If the instantiation is automatic, then what's the literal to 
specify the un-instantiated template?

Bye,
bearophile

Jacob Carlborg <doob me.com> writes:

On 2014-01-17 13:53, bearophile wrote:

 If the instantiation is automatic, then what's the literal to specify
 the un-instantiated template?

Perhaps based on the context, but that might be a bad idea.

-- 
/Jacob Carlborg

"Dicebot" <public dicebot.lv> writes:

On Friday, 17 January 2014 at 13:40:05 UTC, Jacob Carlborg wrote:
 On 2014-01-17 13:53, bearophile wrote:

 If the instantiation is automatic, then what's the literal to 
 specify
 the un-instantiated template?

 Perhaps based on the context, but that might be a bad idea.

I think it is impossible in general case:

pragma(msg, StructSymbol.stringof); // "StructSymbol" or 
"StructSymbol!(void)" ?

Add aliases on top of it and it quickly gets messy.

Jacob Carlborg <doob me.com> writes:

On 2014-01-17 14:44, Dicebot wrote:

 I think it is impossible in general case:

 pragma(msg, StructSymbol.stringof); // "StructSymbol" or
 "StructSymbol!(void)" ?

 Add aliases on top of it and it quickly gets messy.

The compiler would first try the template symbol, if that fails try the 
instantiation.

-- 
/Jacob Carlborg

Manu <turkeyman gmail.com> writes:

On 17 January 2014 22:53, bearophile <bearophileHUGS lycos.com> wrote:

 Jacob Carlborg:


  Yeah, that's a really annoying limitation. I'm wonder if there's a
 bugzilla entry for it.

 If the instantiation is automatic, then what's the literal to specify the
 un-instantiated template?

The context gives everything it needs. It's clearly being used to declare a
variable.

"bearophile" <bearophileHUGS lycos.com> writes:

Manu:

 The context gives everything it needs.

I don't think so. If you pass one of those literals to a template 
by alias, you are passing the template name (the type 
constructor) or the instantiated template (the type)? Both are 
valid usages and I think the compiler can't choose by itself. So 
I think this is a bad idea.

Bye,
bearophile

Jacob Carlborg <doob me.com> writes:

On 2014-01-17 15:47, bearophile wrote:

 I don't think so. If you pass one of those literals to a template by
 alias, you are passing the template name (the type constructor) or the
 instantiated template (the type)? Both are valid usages and I think the
 compiler can't choose by itself. So I think this is a bad idea.

Template name, because you can override that with !() to mean template 
instantiation.

-- 
/Jacob Carlborg

"John Colvin" <john.loughran.colvin gmail.com> writes:

On Friday, 17 January 2014 at 12:18:51 UTC, Manu wrote:
 Observing strange behaviour, just want to know if it's 
 correct...

 struct VertexBuffer(VertexDataType = void) {}

 VertexBuffer x;
   Error: struct VertexBuffer(VertexDataType = void) is used as 
 a type

 auto y = VertexBuffer();
   Error: struct VertexBuffer(VertexDataType = void) cannot 
 deduce template
 function from argument types !()()

 But this works:
 VertexBuffer!() z;


 Why should I need to supply an empty argument list? This 
 defeats the
 purpose of the default arg, and obscures my code in the common 
 case.

 Untyped vertex buffers are the default, and it would be nice to 
 be able to
 declare them trivially.

 Also, those error messages are quite unhelpful.

There's enough subtlety in function identifiers vs function 
results due to optional parenthesis, I'd rather not have the same 
for templates too. Even if it could be made unambiguous, it would 
likely get pretty confusing.

"monarch_dodra" <monarchdodra gmail.com> writes:

On Friday, 17 January 2014 at 12:18:51 UTC, Manu wrote:
 Observing strange behaviour, just want to know if it's 
 correct...

 struct VertexBuffer(VertexDataType = void) {}

 VertexBuffer x;
   Error: struct VertexBuffer(VertexDataType = void) is used as 
 a type

 auto y = VertexBuffer();
   Error: struct VertexBuffer(VertexDataType = void) cannot 
 deduce template
 function from argument types !()()

 But this works:
 VertexBuffer!() z;


 Why should I need to supply an empty argument list? This 
 defeats the
 purpose of the default arg, and obscures my code in the common 
 case.

 Untyped vertex buffers are the default, and it would be nice to 
 be able to
 declare them trivially.

 Also, those error messages are quite unhelpful.

The funny part though is that it works if the template is a 
function.

//----
template foo(T = int)
{
     T foo();
}

void main()
{
     foo(); //Calls foo!int.foo();
}
//----

I guess it's the "()" that saves our butts. Without it, we need 
explicit instantiation:

//----
template foo(T = int)
{
     T foo();
}

void main()
{
     pragma(msg, typeof(foo).stringof);
     pragma(msg, typeof(foo!int).stringof);
}
//----
void
int()
//----