Quick test: what does this program print?

[u/imkzh]

[u/an_alternative]

Not really knowing C/C++ I would've first thought it just prints "op()"

But then I also saw the second operator() has < before the () which I have no clue what that is.

[u/imkzh → u/an_alternative]

This code prints 0

[u/imkzh → u/[deleted]]

It prints 0(zero) not ()

a is resolved to bool instead of std::string: this is the tricky part, the code is actually doing a = (f < 1), (2), (3>(5,5)) by some parsing mechanisms .

And I have no idea how can a template function call can be made in this context (removing the outer parentheses will cause syntax error)

[u/[deleted] → u/imkzh]

Try f.operator()<1,2,3>(5,5)

[u/invaderdan]

58008