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Go's string is guaranteed to be a series of bytes, not Unicode code points. I'm unsure about Java. Rust has a more complicated text model that I won't summarize

Go's string is guaranteed to be a series of bytes, not Unicode code points. I'm unsure about Java. Rust has a more complicated text model that I won't summarize in this post, but it's far better than Python 3's. > In Python 3 you don't have Unicode (as far as you should be concerned), you have text and bytes Python 3 strings store Unicode code points. When you iterate over a Python 3 str, you get back Unicode code points. As mentioned elsewhere, this is not a Unicode scalar value, and can include things like unpaired surrogates. This is also not an extended grapheme cluster, which is the current best-effort description as to what counts as a "single character". So, you really do need to be concerned about what your strings contain. If you don't want people to care, don't give them the ability to iterate, slice, or index into str to retrieve Unicode code points, and leave them as opaque blobs, as some of those other languages do.

takeda 7y ago
> Go's string is guaranteed to be a series of bytes, not Unicode code points. I'm unsure about Java. Rust has a more complicated text model that I won't summarize in this post, but it's far better than Python 3's. Yes, but at this point you're arguing about implementation details. The idea is that if you use it as a string it is string, if you need bytes, you need to perform a conversion. It shouldn't be your concern how it is stored internally. If we are going into Python internals, the string can be stored as multiple versions from basic C-string to unicode code points. If you perform conversion it will cache the result so it can be used in other places. I don't remember the details, since I looked at the code long time ago, but it isn't that simple.
- Jasper_ 7y ago
  I don't know how to explain it any simpler. Iterating over a str type in Python 3 enumerates Unicode code points. The length of a str type is the number of code points it contains. Reversing a str will reverse the Unicode code points it contains (not guaranteed to be a sane operation). Indexing into a str with foo[0] gives you back a str containing a single Unicode code point. This is not an implementation detail, it is fundamental to how the str type in Python 3 operates. I have not talked at any point about the internal storage of this type, just the interface it publicly exposes.
  - lmm 7y ago
    Python 3 strs should not be iterated over, sure. Ban that in your linter, then you're in the same position you would be in Rust. It's a misfeature but it's still a detail.
  - takeda 7y ago
    This is called a leaky abstraction. I can't find a good behavior for a high level language to do it this way. If you use index in a string you always will get something that's invalid, at least in Python or Java you get code points.

takeda 7y ago

> Go's string is guaranteed to be a series of bytes, not Unicode code points. I'm unsure about Java. Rust has a more complicated text model that I won't summarize in this post, but it's far better than Python 3's. Yes, but at this point you're arguing about implementation details. The idea is that if you use it as a string it is string, if you need bytes, you need to perform a conversion. It shouldn't be your concern how it is stored internally. If we are going into Python internals, the string can be stored as multiple versions from basic C-string to unicode code points. If you perform conversion it will cache the result so it can be used in other places. I don't remember the details, since I looked at the code long time ago, but it isn't that simple.

Jasper_ 7y ago
I don't know how to explain it any simpler. Iterating over a str type in Python 3 enumerates Unicode code points. The length of a str type is the number of code points it contains. Reversing a str will reverse the Unicode code points it contains (not guaranteed to be a sane operation). Indexing into a str with foo[0] gives you back a str containing a single Unicode code point. This is not an implementation detail, it is fundamental to how the str type in Python 3 operates. I have not talked at any point about the internal storage of this type, just the interface it publicly exposes.
- lmm 7y ago
  Python 3 strs should not be iterated over, sure. Ban that in your linter, then you're in the same position you would be in Rust. It's a misfeature but it's still a detail.
- takeda 7y ago
  This is called a leaky abstraction. I can't find a good behavior for a high level language to do it this way. If you use index in a string you always will get something that's invalid, at least in Python or Java you get code points.