template specialization

[Rahul]

Hi Everyone,

I have the following code,


template<typename T>
void funn(T a)
{
printf("function invoked...\n");
}

template<>
void funn<int>(int aa)
{
printf("second function is invoked...\n");
}

void funn(int a)
{
printf("third function is invoked...\n");
}


int main()
{
funn(2);
}


And i get the following output,

third function is invoked...

But i expected a compilation error "funn(int) redefined", does the
standard say anything about this?

Thanks in advance ! ! !

 

[v.sobkowski]

Hi Everyone,

I have the following code,

template<typename T>
void funn(T a)
{
printf("function invoked...\n");

}

template<>
void funn<int>(int aa)
{
printf("second function is invoked...\n");

}

void funn(int a)
{
printf("third function is invoked...\n");

}

int main()
{
funn(2);

}

And i get the following output,

third function is invoked...

But i expected a compilation error "funn(int) redefined", does the
standard say anything about this?

Thanks in advance ! ! !

Cause you have 2 different functions.
1: void funn(int);
2: void funn<int>(int)

If you wanna call template function use "funn<int>(2)"

greets

 

[Rahul]

Cause you have 2 different functions.
1: void funn(int);
2: void funn<int>(int)

If you wanna call template function use "funn<int>(2)"

greets

Yes that invokes the second function. Does it mean compiler actually
creates two copies of fun(int)... shouldn't that cause a compilation
error as overloading of function with same signatures is not valid...

 

[Rahul]

Yes that invokes the second function. Does it mean compiler actually
creates two copies of fun(int)... shouldn't that cause a compilation
error as overloading of function with same signatures is not valid...

after all, templates are just code replacement at compile time instead
of pre-processor time... so wouldn't the compiler see it as two
definitions for the same prototype?

 

[Juha Nieminen]

Yes that invokes the second function. Does it mean compiler actually
creates two copies of fun(int)... shouldn't that cause a compilation
error as overloading of function with same signatures is not valid...

They are different functions (they behave differently eg. with respect
to linking), and internally name mangling makes them distinct.

 

[Rahul]

They are different functions (they behave differently eg. with respect
to linking), and internally name mangling makes them distinct.

Does the standard say anything explicitly about such cases? I know
that linker is supposed to remove the duplicate copies of template
functions which are created in multiple translational units...

 

[gnuyuva]

Does the standard say anything explicitly about such cases? I know
that linker is supposed to remove the duplicate copies of template
functions which are created in multiple translational units...

Refer to this post:
http://www.gotw.ca/publications/mill17.htm

HTH