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Inline const expressions have been stabilised (github.com)

submitted 7 months ago by [email protected] to c/rust

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[–] onlinepersona 0 points 7 months ago* (last edited 7 months ago) (2 children)

I'm not getting it. What's the point? It seems very much like a cpp-ism where you can put const in so many places.

const int n2 = 0;    // const object
int const n3 = 0;    // const object (same as n2)
// https://learn.microsoft.com/en-us/cpp/cpp/const-and-volatile-pointers?view=msvc-170
const char *cpch;  // const variable cannot point to another pointer
char * const pchc; // value of pointer is constant

int f() const; // members cannot be modified in this, only read
std::string const f(); // returns a constant

Then there are constant expressions.

Can anybody look at that and tell me it's readable with a straight face? I hope they don't start adding all this stuff to rust.

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[–] [email protected] 4 points 7 months ago

It can be used for producing const values in arbitrary context. Can basically be swapped for c++'s constexpr.

C++'s const does not exist in rust (values are const by default).

[–] fzz 3 points 6 months ago

Nope. This little neat feature mainly is just necessary part of bigger one - const-generics with const bounds.