Templates, token-pasting, defines and literals...

[Jean-Claude Gervais]

Hi,

I'm trying to write a template class that knows its own name.

Specifically, I want it to behave this way -

Say I instantiate a template class like this:

my_vector<int> foo;

I'd like to have a method (let's call it GetClassName) in my_vector that
returns a pointer to the string "int".

Or if the instantiation was done with any other class, like CPoint,
calling ClassName() would return "CPoint".

#define paster( n ) ( "class" #n " is the class" )

template <typename T> class my_vector : public std:vector<T> {

public:

static char * GetClassName(void) { return paster( T ); };

};


But I am having problems with doing this in a template. It seems like
the typename T is being taken literally as "T", the string returned is
always

"class T is the class"

Is there a way?

 

[Panjandrum]

I'm trying to write a template class that knows its own name.

Specifically, I want it to behave this way -

Say I instantiate a template class like this:

my_vector<int> foo;

I'd like to have a method (let's call it GetClassName) in my_vector that
returns a pointer to the string "int".

Or if the instantiation was done with any other class, like CPoint,
calling ClassName() would return "CPoint".

#define paster( n ) ( "class" #n " is the class" )

template <typename T> class my_vector : public std:vector<T> {

public:

static char * GetClassName(void) { return paster( T ); };

};


But I am having problems with doing this in a template. It seems like
the typename T is being taken literally as "T", the string returned is
always

"class T is the class"

The C preprocessor runs ahead of the C++ template processor. Have you
looked at typeid?

 

[Victor Bazarov]

I'm trying to write a template class that knows its own name.

Specifically, I want it to behave this way -

Say I instantiate a template class like this:

my_vector<int> foo;

I'd like to have a method (let's call it GetClassName) in my_vector that
returns a pointer to the string "int".

Or if the instantiation was done with any other class, like CPoint,
calling ClassName() would return "CPoint".

#define paster( n ) ( "class" #n " is the class" )

template <typename T> class my_vector : public std:vector<T> {

public:

static char * GetClassName(void) { return paster( T ); };

};


But I am having problems with doing this in a template. It seems like
the typename T is being taken literally as "T", the string returned is
always

"class T is the class"

Is there a way?

Not really. You could try using 'typeid(T).name()', but there is no
guarantee in the language that it returns anything useful.

V

 

[Michael Olea]

Hi,

I'm trying to write a template class that knows its own name.

You might be interested in the thread: typeid(T).nameOfTheBeast()