CODEWITHSUNDEEP
c++templates
rid
rid

Reputation: 63442

Template instantiation time typeid()

How can I find the type of the template argument at template instantiation time? For example, I'd like the following template to instantiate into 2 different functions, depending on the argument:

template <typename T> void test(T a) {
    if-T-is-int {
        doSomethingWithInt(a);
    } else {
        doSomethingElse(a);
    }
}

When instantiated with an int, the resulting function would be:

void test(int a) { doSomethingWithInt(a); }

and when instantiated with a float for example, it would be:

void test(float a) { doSomethingElse(a); }

Upvotes: 0

Views: 372

Answers (2)

Qaz
Qaz

Reputation: 61910

In your case, it sounds like all you need is two overloaded versions for int and float. There's no behaviour for other types described, so templates aren't necessary.

void test (int i) {
    doSomethingWithInt(i);
}

void test (float f) {
    doSomethingElse(f);
}

If you do need the case of other types, add in a normal templated version. The specific overloads take precedence. For an example, see here.

Upvotes: 1

Rollie
Rollie

Reputation: 4752

template <typename T> void test(T a) {
    doSomethingElse(a);
}

template <> void test(int a) {
    doSomethingWithInt(a);
}

Should work, but you need to consider cases where you get an int &, const int, etc.

Upvotes: 1

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