In Zig, I can do this with no problems:
fn foo() void {
comptime var num: comptime_int = 0;
num += 1;
}
But when I try declaring the variable outside of a function, I get a compile error:
comptime var num: comptime_int = 0;
fn foo() void {
num += 1;
}
fn bar() void {
num += 2;
}
error: expected block or field, found 'var'
Zig version: 0.9.0-dev.453+7ef854682
Use the method used in zorrow . It defines the variable in a function (a block works too), then it returns a struct with functions for accessing it.
You can create a struct that defines get
and set
functions:
const num = block_name: {
comptime var self: comptime_int = 0;
const result = struct {
fn get() comptime_int {
return self;
}
fn increment(amount: comptime_int) void {
self += amount;
}
};
break :block_name result;
};
fn foo() void {
num.increment(1);
}
fn bar() void {
num.increment(2);
}
In the future, you will be able to use a const
with a pointer to the mutable value, and the method shown above will no longer be allowed by the compiler: https://github.com/ziglang/zig/issues/7396
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