[andyferris]

> human-editable

I mean, depends on the human. Most don't know hexadecimal, but know what 3.14 means.

The real issue is why do so many float parsers and printers fail to do exact round tripping? Designing a good algorithm for this was a bit difficult, but these days this is a solved problem.

[johnnyanmac]

If I had to take a slightly snide guess: because these are low level tools, so there's a 90% chance that these parsers/prints are written in C, or ultimately depend on C implementations. As any C programmer would know, C loves to throw "undefined behavior" at any problem it doesn't bother to document. Which is a lot.

That combined with almost zero package management for retrieving things that were solved decades ago means we keep coming into this issue, partially because of the mindset of C programmers.

[account42]

This is just "hur dur C undefined lol" level of a comment.

If you are serious about your data format supporting round tripping you can and should specify the precise ASCII encoding of binary floats and the inverse. If that means implementations have to ship their own float formatter and parser than so be it - no one is tied to whatever comes with their libc, package manager or no package manager.

[johnnyanmac]

I did say slightly snide.

But it isn't just about undefined behavior, it's more about the culture of C and how it approaches package management and sharing (or in this case, doesn't). Even if C has Rust level correctness checking it would have the same issue.

>If you are serious about your data format supporting round tripping you can and should specify the precise ASCII encoding of binary floats and the inverse.

Well I guess we have our answer in the case of seriousness. I'm guessing it didn't matter enough for the implementers, or it did matter but could never actually get it implemented. The reasons for this are numerous, contextual (with context we'll never have), and probably not rooted in technical reasoning.

We are talking about the domain of animation and games, after all. Not mission critical code. There's more wiggle room, especially for the complexity of media around when the format was being developed.