CODEWITHSUNDEEP
c++templates
rontgen
rontgen

Reputation: 81

Passing a general argument to function using template

There are some classes and their relationships are as follows:

class X:A,B
class Y:A,B
class Z:A,B

I want to pass a general type that will inherit from A and B to testFunction using template. My code is as follows:

template<template T:public A, public B>
void testFunction(T generalType)
{
    //do something
}

but my compiler told me that it's error template. How could I fix it?

Upvotes: 4

Views: 87

Answers (2)

songyuanyao
songyuanyao

Reputation: 172904

template<template T:public A, public B> is not valid syntax. You could check the type with std::is_base_of and static_assert, which will trigger a compiler error if wrong type passed.

template <typename T>
void testFunction(T generalType)
{
    static_assert(std::is_base_of<A, T>::value && std::is_base_of<B, T>::value, "T must inherit from A and B.");
}

DEMO

Upvotes: 4

MSalters
MSalters

Reputation: 179799

The standard method to conditionally define a template is std::enable_if<condition>. In this case, you want to check the condition std::is_base_of<A,T>::value && std::is_base_of<B,T>::value

Upvotes: 9

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