• Carl Sturtivant (13/13) Jul 20 2013 struct A {
• bearophile (5/6) Jul 20 2013 Perhaps it's a bug fixed in GIT head. As workaround try:
• Carl Sturtivant (14/18) Jul 20 2013 OK, but now I don't know how to call a templated constructor.
• Jonathan M Davis (16/41) Jul 20 2013 Templated constructors will work with IFTI (Implicit Function Template
• Carl Sturtivant (4/4) Jul 21 2013 That's too bad, because in the real code this example was derived
• Jonathan M Davis (3/6) Jul 21 2013 You could use a factory function instead.
• Carl Sturtivant (8/16) Jul 22 2013 Yes, and I suppose it's not that awful of a work-around. Only D
• Jonathan M Davis (4/21) Jul 22 2013 Well, ideally it would work, and there's a decent chance that it will in...
• Jonathan M Davis (8/25) Jul 20 2013 As of 2.063, you can't overload a templated function with a non-template...

"Carl Sturtivant" <sturtivant gmail.com> writes:

struct A {
	string s;
	int n;
	this( string s) { this.s = s; }
	this( int k)( int n) { this.n = n - k; }
}

compiled with dmd gives an error message as follows.

constr_conflict.d(5): Error: template 
constr_conflict.A.__ctor(int k)(int n) conflicts with constructor 
constr_conflict.A.this at constr_conflict.d(4)

The exact details seem unimportant except that one constructor 
has compile-time parameters and the other does not.

What is the conflict exactly?

"bearophile" <bearophileHUGS lycos.com> writes:

Carl Sturtivant:

 What is the conflict exactly?

Perhaps it's a bug fixed in GIT head. As workaround try:

this()(string s)

Bye,
bearophile

"Carl Sturtivant" <sturtivant gmail.com> writes:

On Saturday, 20 July 2013 at 22:33:00 UTC, bearophile wrote:
 Carl Sturtivant:

 What is the conflict exactly?

 Perhaps it's a bug fixed in GIT head. As workaround try:

 this()(string s)

OK, but now I don't know how to call a templated constructor.

void main() {
	A x = A!3(99);
}

added to the file containing the original class with the 
workaround edited in doesn't compile, and curiously the error 
message is produced twice:

constr_conflict.d(9): Error: template instance A!(3) A is not a 
template declaration, it is a struct
constr_conflict.d(9): Error: template instance A!(3) A is not a 
template declaration, it is a struct

What do I need to do to make a call of this constructor call 
compile?

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Sunday, July 21, 2013 05:17:03 Carl Sturtivant wrote:
 On Saturday, 20 July 2013 at 22:33:00 UTC, bearophile wrote:
 Carl Sturtivant:
 What is the conflict exactly?

 
 Perhaps it's a bug fixed in GIT head. As workaround try:
 
 this()(string s)

 
 OK, but now I don't know how to call a templated constructor.
 
 void main() {
 	A x = A!3(99);
 }
 
 added to the file containing the original class with the
 workaround edited in doesn't compile, and curiously the error
 message is produced twice:
 
 constr_conflict.d(9): Error: template instance A!(3) A is not a
 template declaration, it is a struct
 constr_conflict.d(9): Error: template instance A!(3) A is not a
 template declaration, it is a struct
 
 What do I need to do to make a call of this constructor call
 compile?

Templated constructors will work with IFTI (Implicit Function Template 
Instantiton - i.e. where the types are inferred from the arguments), but I'm 
not sure that it works when you have to explicitly instantiate them. I know 
that if the type itself is templated as wel, then you're out of luck, because 
the language provides no way to explicitly instantiate both (though maybe you 
could do it by aliasing the explicitly instantiated templated type and then 
explicitly instantiating the constructor using the alias).

I'd argue that your example should work, because the type itself isn't 
templated, and the compiler should be able to determine that you're trying to 
explicitly instantiate the constructor, not the type, but I don't know what 
the compiler devs' stance on it would be.

I'd suggest opening a bug report: http://d.puremagic.com/issues

But if your example doesn't work, then I don't know of any to explicitly 
instantiate a templated constructor.

- Jonathan M Davis

"Carl Sturtivant" <sturtivant gmail.com> writes:

That's too bad, because in the real code this example was derived 
from I can't have type inference call the right constructor as 
there are two constructors with the same run-time argument types.

I'll put in a bug report.

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Sunday, July 21, 2013 16:25:15 Carl Sturtivant wrote:
 That's too bad, because in the real code this example was derived
 from I can't have type inference call the right constructor as
 there are two constructors with the same run-time argument types.

You could use a factory function instead.

- Jonathan M Davis

"Carl Sturtivant" <sturtivant gmail.com> writes:

On Sunday, 21 July 2013 at 18:37:23 UTC, Jonathan M Davis wrote:
 On Sunday, July 21, 2013 16:25:15 Carl Sturtivant wrote:
 That's too bad, because in the real code this example was 
 derived
 from I can't have type inference call the right constructor as
 there are two constructors with the same run-time argument 
 types.

 You could use a factory function instead.

 - Jonathan M Davis

Yes, and I suppose it's not that awful of a work-around. Only D
invited this nice technique in the interesting situation I am in,
and I like simplicity and elegance, and I like to supply nice
explanations based thereupon. I do hope this gets to work
eventually in a later version. :)

Thanks for the input,

Carl.

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Tuesday, July 23, 2013 05:42:10 Carl Sturtivant wrote:
 On Sunday, 21 July 2013 at 18:37:23 UTC, Jonathan M Davis wrote:
 On Sunday, July 21, 2013 16:25:15 Carl Sturtivant wrote:
 That's too bad, because in the real code this example was
 derived
 from I can't have type inference call the right constructor as
 there are two constructors with the same run-time argument
 types.

 
 You could use a factory function instead.
 
 - Jonathan M Davis

 
 Yes, and I suppose it's not that awful of a work-around. Only D
 invited this nice technique in the interesting situation I am in,
 and I like simplicity and elegance, and I like to supply nice
 explanations based thereupon. I do hope this gets to work
 eventually in a later version. :)

Well, ideally it would work, and there's a decent chance that it will in the 
future, but for now, we're out of luck.

-  Jonathan M Davis

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Sunday, July 21, 2013 00:10:40 Carl Sturtivant wrote:
 struct A {
 	string s;
 	int n;
 	this( string s) { this.s = s; }
 	this( int k)( int n) { this.n = n - k; }
 }
 
 compiled with dmd gives an error message as follows.
 
 constr_conflict.d(5): Error: template
 constr_conflict.A.__ctor(int k)(int n) conflicts with constructor
 constr_conflict.A.this at constr_conflict.d(4)
 
 The exact details seem unimportant except that one constructor
 has compile-time parameters and the other does not.
 
 What is the conflict exactly?

As of 2.063, you can't overload a templated function with a non-templated 
function (or vice versa). That bug has finally been fixed in git master, but it 
hasn't been released yet. The typical way to workaround the problem is to 
templatize the non-templated function, which you can do by giving it an empty 
template parameter list.

this()(string S) {...}

- Jonathan M Davis