StaticBitSet with a variable length

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1

I am trying to create a set of StaticBitSets whose length is not known at compile time; stringLength is read from the command line, like this: std.bit_set.StaticBitSet(stringLength). This fails with

src/bitset_chromosome_generator.zig:18:75: error: unable to evaluate comptime expression
    const output = try generate(allocator, prng, std.bit_set.StaticBitSet(stringLength), numStrings);

Is there any workaround for this, other than generating the code and building it on the fly?

2

Then you should use a DynamicBitSet (or DynamicBitSetUnmanaged since you seem to store the allocator elsewhere).

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3

The issue here is that while StaticBitSet(number) is a type, DynamicBitSet is not. Some important refactoring is needed. I don’t know, however, if there will be a noticeable change in performance.
The problem is a bit more general, maybe, namely, how to work with variable types in run time. Might be an unsolvable problem in this context, since it clashes with Zig philosophy.

4

how to work with variable types in run time.

Well basically you have two options. Either you allocate the memory range you need with a DynamicBitSet, or if you know the maximum size, then you can also always use StaticBitSet of that maximum length.

I don’t know, however, if there will be a noticeable change in performance.

Generally, as long as you don’t allocate or free memory constantly, it shouldn’t make a measurable performance difference. However if you are worried about performance, then you should measure it. This is always better than speculating.

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