Hello fellow WebKittens,

I’ve noticed over time that we don’t have standard way that we enable versions 
of template functions/classes (flasses?). For the most part it seems that 
people use std::enable_if, although, it seems like it is attached to every 
possible place in the function/class.

I propose that we choose a standard way to conditionally enable a template.

There are a ton of options; my personal favorite is to add the following macro:

#define ENABLE_TEMPLATE_IF(condition) static_assert(condition, “template 

Then have every function do:

template<typename T>
void foo(…)
    ENABLE_TEMPLATE_IF(std::is_same<T, int>::value);

And classes:

template<typename T>
class Foo {
    ENABLE_TEMPLATE_IF(std::is_same<T, int>::value);

I like this proposal because it doesn’t obstruct the signature/declaration of 
the function/class but it’s still obvious when the class is enabled. Obviously, 
I think we should require that this macro is the first line of the function or 
class for visibility. Does anyone else have thoughts or ideas?


P.S. in case you are wondering why this macro works (ugh C++), it’s because if 
there is any compile time error in a template it cannot be selected as the 
final candidate. In my examples, if you provided a type other than int foo/Foo 
could not be selected because the static_assert condition would be false, which 
is a compile error.
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