3 ms·

Why use floating point for timestamps? In practice, floating point timestamps have a constant precision throughout their life. That is, the exponent has the s

by mlyle 5y ago

Why use floating point for timestamps? In practice, floating point timestamps have a constant precision throughout their life. That is, the exponent has the same value for a really long time, and you don't get any benefit from the "floating" aspect. As another poster points out, overflow/NaN/infinity is the one nice thing you get. But you pick up all the idiosyncrasies of floats, too. As you point out, float64 is worse than int64_t at attaining a given level of precision for a reasonable amount of time. You do point out that floats "seamlessly upgrade" to increased precision, and this is kind of nice. But if we're picking a 128 bit type, there should be no upgrading needed ever. It just doesn't make sense.

midjji 5y ago
Because in every situation I have ever run into a floating point timestamp behaves more intuitively, and when I started converting my programs to use floating point timestamps almost every function that used timestamps lost dozens of hard to understand special cases that accounted for int overflow, unsignedness, etc problems. Problems which every single one had bit me in the ass at least once before I wrote the code managing the special case, and of which nearly every single one had at least one bug in it. See the revisions to std::midpoint for great examples of how hard this is to do right. However, because float128 overrepresents all the older basic type variants, it becomes trivial. If the code could possibly have been made to work for any of them, it will automatically always work for float128. Its got more to do with how intuitively the timestamp behaves, and that you can use seconds as the unit everywhere and no longer need to keep track of if this wait function took seconds or milliseconds. Using infty to indicate a timeout function should block indefinetly is also much more intuitive than using 0.

by mlyle 5y ago

midjji 5y ago

Because in every situation I have ever run into a floating point timestamp behaves more intuitively, and when I started converting my programs to use floating point timestamps almost every function that used timestamps lost dozens of hard to understand special cases that accounted for int overflow, unsignedness, etc problems. Problems which every single one had bit me in the ass at least once before I wrote the code managing the special case, and of which nearly every single one had at least one bug in it. See the revisions to std::midpoint for great examples of how hard this is to do right. However, because float128 overrepresents all the older basic type variants, it becomes trivial. If the code could possibly have been made to work for any of them, it will automatically always work for float128. Its got more to do with how intuitively the timestamp behaves, and that you can use seconds as the unit everywhere and no longer need to keep track of if this wait function took seconds or milliseconds. Using infty to indicate a timeout function should block indefinetly is also much more intuitive than using 0.