Template type is a template

[entroika]

Suppose we have a template

template <class X>
class NestedTemplate { ... };

template <class A, class T>
class MainTemplate { ... };

class SampleClass {
private:
  MainTemplate<NestedTemplate<char>,float> x;
public:
  // methods
};

code above compiles but when running I get a "memory could not be written" error

I've tried it like this:

template <class X>
class NestedTemplate { ... };

template <class A, class T>
class MainTemplate { ... };

class FakeClass { public: NestedTemplate<char> c; };

class SampleClass {
private:
  MainTemplate<FakeClass,float> x;
public:
  // methods
};

and it didn't work...

I can't figure out what I should change. I'm novice using templates. Simple usage described in most manuals went ok, but I got stucked here. I can solve this without templates but it'll be dirty so I would like to learn how to do it correctly.

Thanks in advance for any help.

[Athar]

There's nothing wrong with the code samples themselves, so the error must be in the parts you omitted.

[entroika]

I've just got on this http://stackoverflow.com/questions/7282971/syntax-of-c-template-template-parameters

Maybe I should make it as follows:

template <template <class> class A, class T>
class MainTemplate { ... };

But then the question is: What can I do if I want a template to accept both Type and Template parameters ??

[Athar]

There's no difference between template types and "normal" types. Which brings us back to my previous reply.

[Pravesh Koirala]

don't know about you guys, but this code worked just fine for me..

#include <iostream>
using namespace std;

template <class Class1DataType>
class Class1
{

  public:
  Class1DataType Class1Data;
  void PrintData()
  {
    cout << Class1Data<<endl;
  }
};

template <class T1, class T2>
class Class2
{
    public:

    T1 Class1Instance;    // will be using class1 here
    T2 B;                   //Some variable

    void PrintData()
    {
        Class1Instance.PrintData();
        cout << B<<endl;
    }


};
class SampleClass
{
    public:
    Class2<Class1<char>,float> Something;
    SampleClass()
    {
        Something.Class1Instance.Class1Data = 'A';
        Something.B = 3.212;
        Something.PrintData();
    }
};
int main()
{
    SampleClass sample;
    return 0;
}

[entroika]

Athar, thanks you were right in "There's no difference between template types and "normal" types"

But this is what I've found out by trying different methods of doing what I need...

The following works:

template<class A, class B> class FirstTemplate {...};

class SimpleClass {
private:
  FirstTemplate<MyType1,MyType2> x;
  // MyType1 and MyType2 are normal types, not template types, but i'm pretty sure it'll work for templates too
}

but if we add another class like this:

// code above +

class AnotherClass {
public:
  SimpleClass a,b;
};

then I get the "refferenced memory could not be written" error.

Does anyone has a clue why ?

[Athar]

There's something wrong elsewhere in your code. Probably in one of the constructors.

[entroika]

Exact error is

The instruction at "0x7c9101b3" referenced memory at "0x0044b5b6". The memory could not be "written".

[Athar]

Doesn't help. Code.
Or run the debugger to see which line causes it.