C++: Can we avoid to systematically specify all the template types?

Asked Jan 28 '19 at 20:17

Active Jan 28 '19 at 20:20

Viewed 61 times

I have a template class where the template definition if very long

template<typename firstType, typename secondType, typename thirdType, typename fourthType, typename fifthType, typename sixthType>

In the .cpp file, writing this entire template in front of each function definition is long and make reading a little difficult. Consider this set function

template<typename firstType, typename secondType, typename thirdType, typename fourthType, typename fifthType, typename sixthType>
void myClass<firstType, secondType, thirdType, fourthType, fifthType, sixthType>::set(firstType x)
{
   ...
}

It would be nice to be able to do

TEMPLATEDEFINITIONS
void myClass<MYTEMPLATES>::set(double x)
{
   ...
}

instead and the compiler would somehow knows to replace TEMPLATEDEFINITIONS and MYTEMPLATES with the appropriate strings. Is something like that possible (without having to sed in the makefile)?

edited Jan 28 '19 at 20:20

asked Jan 28 '19 at 20:17

Remi.b

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5

Use a variadic template instead and just constrain the pack size? – NathanOliver Jan 28 '19 at 20:19
1

Macros to the rescue! :) – Rakete1111 Jan 28 '19 at 20:20
3

Also, see [this](https://stackoverflow.com/questions/495021/why-can-templates-only-be-implemented-in-the-header-file) about putting template code in a cpp file – NathanOliver Jan 28 '19 at 20:22
6

You could pull all of those types into a traits class, which would let you write all of your functions like `template void myClass::set(typename TRAITS::firstType x)` – 0x5453 Jan 28 '19 at 20:23
Put the definition inside the class directly ? – Jarod42 Jan 28 '19 at 22:13
Er, I know we don’t like them, but… macros? Also, why are your template definitions in a `.cpp`? – Davis Herring Jan 29 '19 at 04:32

C++: Can we avoid to systematically specify all the template types?

0 Answers0