is there any ways of making unique hashes for each variable in compile time.
C++ allows block scopes which can result in same named variables inside one function so i cannot just do:
#define MACRO(...) ConstevalHash(__PRETTY_FUNCTION__ #__VA_ARGS__)
int variable = 0;
printf("id %d n", MACRO(variable));
in compiled file should look like:
printf("id %d n", 345908340) // unique hash
I thought of trying to get static memory address of each variable using consteval tricks but im afraid that is not possible with current cpp.
EDIT:
This is solving issue with compile time counters.
Current solution has been just:
#define MACRO(...) __VA_ARGS__.CachedID // static constexpr int CachedID ;
Var<ID, int> Variable = 0; // Id creates unique id using counter
MACRO(variable);
This disallows usage of auto which is not very good solution for any api.
About block scopes
void Function()
{
{ int var = 0; MACRO(var); }
{ int var = 0; MACRO(var); }
}
while(true)
{
Function();
}
Both of these hashes should be different but they should remain the exact same in every tick inside a loop that’s why compile time coding is required.
17
I came up with this:
template <class T> struct var {
using hash_type = unsigned;
using value_type = T;
value_type value;
const hash_type cached_id;
constexpr var(const value_type the_value) noexcept
: value(the_value)
, cached_id([]{ static hash_type k; return k++; }())
{}
constexpr operator auto() noexcept { return value; }
};
template <class T> var(T const&) -> var<T>;
Live on Compiler Explorer
No macros.
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