Re: Template trouble

Subject: Re: Template trouble

From: Adin Hunter Baber <email@hidden>

Date: Mon, 28 Aug 2006 17:29:14 -0500

Delivered-to: email@hidden

On 2006 Aug 28, at 3:00 PM, Edward K. Chew wrote:

Oh, I forgot to mention, I have run into trouble with template specialization. For example, I have a function along the lines:

template <typename T> UInt32 myHashFunction(T value, int hashBitLength);

I specialized this for C strings:

template <> UInt32 myHashFunction(const char *str, int hashBitLength);

You didn't declare the specialization correctly. Try this way:

template<typename T>

void dostuff(T &t)

{

CFShow(CFSTR("Generic Do Stuff"));

}

template<>

void dostuff<int>(int &t)

{

CFShow(CFSTR("Int Do Stuff"));

}

typedef int* intptr; // because gcc chokes on directly declaring a reference to a pointer

template<>

void dostuff<int*>(intptr &t)

{

CFShow(CFSTR("Int* Do Stuff"));

}

int main(int argc, char* argv[])

{

OSStatus error = noErr;

char c = 'c';

int i = 5;

int *p = &i;

dostuff(c);

dostuff(i);

dostuff(p);

return error;

}

It give me the following output:

Generic Do Stuff

Int Do Stuff

Int* Do Stuff

Another important note. At least with gcc, you need to keep the const and references specifiers consistent across the specializations.

If the initial template is declared like this:

template<typename T> void dostuff(const T &t);

Then you need to declare the other ones like this:

template<> void dostuff<int>(const int &t);

template<> void dostuff<int*>(const intptr &t);

Adin Hunter Baber

email@hidden

"The more I learn, the more I learn how little I know."

-- Socrates

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Follow-Ups:

Re: Template trouble
- From: Steve Checkoway <email@hidden>

References:

>FSRef_fopen alternative (From: "Edward K. Chew" <email@hidden>)

>Template trouble (From: "Edward K. Chew" <email@hidden>)

>Re: Template trouble (From: "Edward K. Chew" <email@hidden>)