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digitalmars.D.learn - Some help on Mixin Template at Class level.

reply Matthew Ong <ongbp yahoo.com> writes:
Hi,

As the documentation at D ONLY shows template at functions level and 
also ONLY the content of a class but without the definition of a class.
Could this code be working? Or did I miss out some syntax.

mixin template AType(alias T, U, alias V){
class T : ClassC { // Class level Template
private:
     U value;
public:
     this(){}
     void print(){}
         mixin V;
} // End Class
}

class ClassC {}

mixin template btype() {
     void someFunction() {}; // Content of a class.

}

mixin AType!("ClassB", string, btype);

void main() {
     ClassC r = new ClassB();
}


--------  Build Commands:  --------
-od"bin"
-of"bin\TestTemplate.exe"

-I"src"

"src\Sample.d"

src\Sample.d(20): Error: undefined identifier ClassB, did you mean class 
ClassC?
src\Sample.d(20): Error: ClassB is used as a type

Thanks very much for helping out.

-- 
Matthew Ong
email: ongbp yahoo.com
May 21 2011
parent reply "Simen Kjaeraas" <simen.kjaras gmail.com> writes:
On Sat, 21 May 2011 10:54:54 +0200, Matthew Ong <ongbp yahoo.com> wrote:


 mixin template AType(alias T, U, alias V){
 class T : ClassC { // Class level Template


This gives you a class called T. You seem to want it to have the name
you pass as a string, in which case you have to use string mixins.


 private:
      U value;
 public:
      this(){}
      void print(){}
          mixin V;
 } // End Class
 }

 class ClassC {}

 mixin template btype() {
      void someFunction() {}; // Content of a class.

 }

 mixin AType!("ClassB", string, btype);

 void main() {
      ClassC r = new ClassB();
 }


As mentioned above, in order to use the name from the template parameter
you need to use string mixins. Here is how I would do it:

string ATypeGenerator( string name ) {
     return "class " ~ name ~ " : ClassC {
private:
     U value;
public:
     this(){}
     void print(){}
     mixin V;
}";
}

mixin template AType( string name, U, alias V ) {
     mixin( ATypeGenerator( name ) );
}

mixin AType!("ClassB", string, btype);

void main() {
     ClassC r = new ClassB();
}


-- 
Simen
May 21 2011
parent reply Matthew Ong <ongbp yahoo.com> writes:
On 5/21/2011 5:12 PM, Simen Kjaeraas wrote:

 On Sat, 21 May 2011 10:54:54 +0200, Matthew Ong <ongbp yahoo.com> wrote:


 mixin template AType(alias T, U, alias V){
 class T : ClassC { // Class level Template


 This gives you a class called T. You seem to want it to have the name
 you pass as a string, in which case you have to use string mixins.


 private:
 U value;
 public:
 this(){}
 void print(){}
 mixin V;
 } // End Class
 }

 class ClassC {}

 mixin template btype() {
 void someFunction() {}; // Content of a class.

 }

 mixin AType!("ClassB", string, btype);

 void main() {
 ClassC r = new ClassB();
 }


 As mentioned above, in order to use the name from the template parameter
 you need to use string mixins. Here is how I would do it:

 string ATypeGenerator( string name ) {
 return "class " ~ name ~ " : ClassC {
 private:
 U value;
 public:
 this(){}
 void print(){}
 mixin V;
 }";
 }

 mixin template AType( string name, U, alias V ) {
 mixin( ATypeGenerator( name ) );
 }

 mixin AType!("ClassB", string, btype);

 void main() {
 ClassC r = new ClassB();
 }


Hi, Thanks for the respond.
I am really new to D.
Using your code I have this error:

src\Sample.d(16): Error: undefined identifier btype, did you mean 
template AType(string name,U,alias V)?
src\Sample.d(16): Error: mixin AType!("ClassB",string,_error_) does not 
match template declaration AType(string name,U,alias V)

Could you please ensure it is compilable code and so that I can test the 
template shown by you.

-- 
Matthew Ong
email: ongbp yahoo.com
May 21 2011
parent reply "Simen Kjaeraas" <simen.kjaras gmail.com> writes:
On Sat, 21 May 2011 11:40:22 +0200, Matthew Ong <ongbp yahoo.com> wrote:


 Using your code I have this error:

 src\Sample.d(16): Error: undefined identifier btype, did you mean  
 template AType(string name,U,alias V)?
 src\Sample.d(16): Error: mixin AType!("ClassB",string,_error_) does not  
 match template declaration AType(string name,U,alias V)

 Could you please ensure it is compilable code and so that I can test the  
 template shown by you.


Sorry about that.


string ATypeGenerator( string name ) {
     return "class " ~ name ~ " : ClassC {
private:
     U value;
public:
     this(){}
     void print(){}
     mixin V;
}";
}

mixin template AType( string name, U, alias V ) {
     mixin( ATypeGenerator( name ) );
}

class ClassC {}

mixin template btype() {
     void someFunction() {}; // Content of a class.
}

mixin AType!("ClassB", string, btype);

void main() {
     ClassC r = new ClassB();
}

-- 
   Simen
May 22 2011
parent reply Matthew Ong <ongbp yahoo.com> writes:
On 5/23/2011 2:17 AM, Simen Kjaeraas wrote:

 On Sat, 21 May 2011 11:40:22 +0200, Matthew Ong <ongbp yahoo.com> wrote:


 Using your code I have this error:

 src\Sample.d(16): Error: undefined identifier btype, did you mean
 template AType(string name,U,alias V)?
 src\Sample.d(16): Error: mixin AType!("ClassB",string,_error_) does
 not match template declaration AType(string name,U,alias V)

 Could you please ensure it is compilable code and so that I can test
 the template shown by you.


 Sorry about that.


 string ATypeGenerator( string name ) {
 return "class " ~ name ~ " : ClassC {
 private:
 U value;
 public:
 this(){}
 void print(){}
 mixin V;
 }";
 }

 mixin template AType( string name, U, alias V ) {
 mixin( ATypeGenerator( name ) );
 }

 class ClassC {}

 mixin template btype() {
 void someFunction() {}; // Content of a class.
 }

 mixin AType!("ClassB", string, btype);

 void main() {
 ClassC r = new ClassB();
 }


Thanks simen. I have solve that issue.

Someone also pointed out:

template mydef(string name){
}

mixin(mydef!("abc"));

The above are NOT shown up left hand side of that when we click on 
Language Reference
http://www.digitalmars.com/d/2.0/lex.html
And also here.
http://www.digitalmars.com/d/2.0/comparison.html

not the same as:
mixin template mydeff(T){
...
}

mixin mydeff!(string);

Some centralized documentation is needed for D.

-- 
Matthew Ong
email: ongbp yahoo.com
May 23 2011
parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
On 5/23/11, Matthew Ong <ongbp yahoo.com> wrote:

 Someone also pointed out:

 template mydef(string name){
 }

 mixin(mydef!("abc"));

 The above are NOT shown up left hand side of that when we click on
 Language Reference


You're probably looking for this:

http://www.digitalmars.com/d/2.0/mixin.html
May 23 2011