[POC] Named function arguments using @name

[RPeschke]

[POC] Named function arguments using @name

Status: This is a proof of concept only. It does not meet the quality, testing, or design bar for merging into the main repository. The goal is to explore the idea and see whether there is interest in this concept at all.

Summary

Many modern programming languages provide named function arguments. This PR experiments with bringing a similar feature into the cppfront/C++ world. In this proposal, the @ symbol introduces a name which can then be used, for example, as a named function argument.

Syntax (POC)

• @name = value introduces a name-value pair usable at call sites and in lightweight record-like objects.

Example file

examples/named_function_arguments.cpp2 demonstrates calling a function with named arguments in any order:

variadic_template( 1, 2.5, @argument4 = std::string("five"), @argument3 = 12 );

It also shows using the same mechanism to create variadic objects:

nt1 := nt::ntuple{
    @a = 1,
    @b = 2.5,
    @c = std::string("three"),
    @d = '4'
};

std::cout << nt1.a << std::endl;  // prints 1
std::cout << nt1 << std::endl;    // prints | a: 1 | b: 2.5 | c: three | d: 4 |

Question

Would the authors be interested in seeing this concept developed further (with proper design notes, diagnostics, tests, and performance considerations), or should it remain a one-off experiment?

[gregmarr]

This discussion links to some past discussions that you might find helpful: #870

[RPeschke]

Ah ok thanks for the link