[squeak-dev] Recent change in byte array at:put:

Jakob Reschke jakob.reschke at student.hpi.de
Sun Jul 30 09:02:14 UTC 2017

Simple "solution" to editing: treat (encoded) Strings as immutable.

For editing/stringbuilding, use a WideString or a special kind of stream
(MultiByteBinaryOrTextStream or how is it called) plus additional support
for inserting in the middle if desired. I remember somebody proposing Ropes
when discussing a reformation of strings previously. Could be interesting
at "edit-time".

For (in-memory) storage, encoded Strings should maybe just be ByteArrays
paired with some TextConverter-like thing or at least a spec of the
encoding so you can fetch Characters or configure streams from it on demand.

If licensing permits it one could also have a look at how the OpenJDK deals
with UTF-16 in StringBuilder.

Am 30.07.2017 03:20 schrieb "tim Rowledge" <tim at rowledge.org>:

> On 29-07-2017, at 12:48 PM, Nicolas Cellier <nicolas.cellier.aka.nice at gmai
l.com> wrote:
> Absolutely,
> to me a String is a sequence of characters.
> squeakToUtf8 is a hack that makes us consider a String as a sequence of
codePoints whose encoding is in the eye of the beholder (or implicitly in
the Context - the Smalltalk one).
> I's not very object oriented and quite fragile.
> We started to clean Multilingual but never finished the job…

Yes, that’s pretty much how I see it. Currently the utf8 ‘string’ is just
kept as a byte string and the user is expected to understand that it is in
a rather dangerous state.

> It's difficult to finish it, because we value backward compatibility.
> So maybe the ByteArray change was a bit radical with this respect.

Backward compatibility can sometimes drive you to loud swearing!

Maybe a new message to return the bytearray of the uft8 data could be
added, leaving the old one alone. We should probably consider making an
actual UTF8String class, though I did try to work out the best thing to do
for that several years ago for NuScratch and got lost in the tangles.
Editing the damn things is a pain, to say the leat, so you get to thinking
about having the canonical string as an instvar and a byte array and edits
work on the String which gets converted at the end of the edit to update
bytearray. Or the other way around… or… aaargh!

tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
Useful random insult:- Immune from any serious head injury.
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