3 ms·

It's been many years since I wrote any Go for a living, but does Go seriously lack a way to say "foo is probably 32 bytes, give me the 32 byte array, and if I'm

It's been many years since I wrote any Go for a living, but does Go seriously lack a way to say "foo is probably 32 bytes, give me the 32 byte array, and if I'm wrong about how big foo is, let me handle that" ? If the caller was expected to provide a duration and your language has a duration type, you presumably wouldn't take a string, parse that and if it isn't a duration return some not-a-duration error, you'd just make the parameter a duration. It seems like this ought to be a similar situation.

throwaway894345 1y ago
> It's been many years since I wrote any Go for a living, but does Go seriously lack a way to say "foo is probably 32 bytes, give me the 32 byte array, and if I'm wrong about how big foo is, let me handle that" ? Not in the static type signature, but you can do that as a runtime check either by casting and handling the potential panic (as described above) or by checking the size and returning an error if it's not as expected, which is what the library does.
deleted 1y ago
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0x696C6961 1y ago
How did you write Go for a living and simultaneously not know anything about the language?
- tialaramex 1y ago
  Because ten years ago Go was a rather different language? Because I don't work only in languages where I would consider myself an expert and so be confident I know every feature ? This reminds me of a C programmer confidently insisting to me that bool had "always" been a keyword. Nope, only since C23 - but it had been used like a keyword anyway. So it makes sense many practitioners wouldn't know that.
  - 0x696C6961 1y ago
    > Because ten years ago Go was a rather different language? It was not.
des429 1y ago
Who are u expecting an answer from?
mjevans 1y ago
You can create a new empty array of variable size backed by a 32 Byte array as it's starting size. The difference is really that [32]Byte is a single pointer (in compiler hands that you never touch) to a slab of 32 bytes of memory; the []Byte (of internal size 32 use 0-32) has the current allocated size, current used size, and a pointer (none of which you directly touch but two of which are trivial to affect with language semantics) values that point to a 32 Byte backing array. The only time this matter is timing or performance critical code. With respect to cryptography, timing might be critical for performance, but it's absolutely critical for never taking _variable_ time to perform an operation based on data as well as not on key. In that respect this doesn't matter.

throwaway894345 1y ago

> It's been many years since I wrote any Go for a living, but does Go seriously lack a way to say "foo is probably 32 bytes, give me the 32 byte array, and if I'm wrong about how big foo is, let me handle that" ? Not in the static type signature, but you can do that as a runtime check either by casting and handling the potential panic (as described above) or by checking the size and returning an error if it's not as expected, which is what the library does.

deleted 1y ago

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0x696C6961 1y ago

How did you write Go for a living and simultaneously not know anything about the language?

tialaramex 1y ago
Because ten years ago Go was a rather different language? Because I don't work only in languages where I would consider myself an expert and so be confident I know every feature ? This reminds me of a C programmer confidently insisting to me that bool had "always" been a keyword. Nope, only since C23 - but it had been used like a keyword anyway. So it makes sense many practitioners wouldn't know that.
- 0x696C6961 1y ago
  > Because ten years ago Go was a rather different language? It was not.

des429 1y ago

Who are u expecting an answer from?

mjevans 1y ago

You can create a new empty array of variable size backed by a 32 Byte array as it's starting size. The difference is really that [32]Byte is a single pointer (in compiler hands that you never touch) to a slab of 32 bytes of memory; the []Byte (of internal size 32 use 0-32) has the current allocated size, current used size, and a pointer (none of which you directly touch but two of which are trivial to affect with language semantics) values that point to a 32 Byte backing array. The only time this matter is timing or performance critical code. With respect to cryptography, timing might be critical for performance, but it's absolutely critical for never taking _variable_ time to perform an operation based on data as well as not on key. In that respect this doesn't matter.