Date: Wed, 12 Mar 2025 12:49:46 +0100
Well, I would love this for the ease of use.
enum class or struct does indicate some object oriented programming so it does look like a decently good idea to introduce operator overloading as a method for those.
By default they would create a switch statement functions that will change between every type to every type. But you should be able to specify them explicitly or even just delete them.
enum struct {
a = 0 | “zero”,
b = 3;
static constexpr operator const char* (int I){
switch(i){
case a: return “zero”;
case b: return ””; // maybe it should either throw or return an error of all of the types are not convertible to the other type
}
}
};
Cheers, Filip
Wiadomość napisana przez Sebastian Wittmeier via Std-Proposals <std-proposals_at_[hidden]> w dniu 12 mar 2025, o godz. 10:39:
AW: [std-proposals] lambdas in enums If it is just two types, int and a more complex type, you could build it around a std::map.
In the future one could use reflection and meta-programming to generate more of such types at compile-time
-----Ursprüngliche Nachricht-------
Von: Filip via Std-Proposals <std-proposals_at_[hidden]>
Gesendet: Mi 12.03.2025 10:13
Betreff: Re: [std-proposals] lambdas in enums
An: std-proposals_at_[hidden];
CC: Filip <fph2137_at_[hidden]>; std-proposals_at_[hidden];
What about having enum with alternate types?enum struct{a = 0,b<int> = 3,b<const char*> = “three”};Orenum struct {a = 0,b = 3 | “three”};The user can use static_cast to change from one to the other.In my cases something like this would eliminate functions and make it clearer what enums are taken care of.Cheers, FilipWiadomość napisana przez Robin Savonen Söderholm via Std-Proposals <std-proposals_at_[hidden]> w dniu 12 mar 2025, o godz. 07:39:I paraphrase Mateusz Pusz from one of his courses: prefer free functions over member functions.
ADL is a thing in C++ and I see no benefits of this proposal vs to utilize ADL and just define a free "to_string"-method in the enclosing namespace. Free functions found with ADL are just as much part of a types API as their member functions.// Robin
--On Wed, Mar 12, 2025, 06:47 Simon Schröder via Std-Proposals <std-proposals_at_[hidden]> wrote:
> On Mar 12, 2025, at 2:23 AM, Dmitrii Shabalin via Std-Proposals <std-proposals_at_[hidden]> wrote:
>
> If you have any idea how to have a function inside in the enum, please, share your idea with an example.
My first thought was that instead of allowing enums to have member functions I would put an enum inside a class:
class Test
{
public:
// not en enum class on purpose!
enum TestEnum { test_value = 0 };
static string_view to_string(TestEnum);
}
Declaring a variable is slightly more to type:
Test::TestEnum e = test_value;
and you can‘t call it as a member function:
e.to_string(); // not possible
However, the “member function call” could be solved differently. We could, once more, try to allow for member call syntax to also look for “free standing” (or otherwise scoped functions) that take the type as the first parameter. (With this solution it doesn’t really matter if we put the enum inside a namespace or class.)
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Received on 2025-03-12 11:49:59