[Dlang-study] [rcstring] Defining rcstring

Marc Sch├╝tz schuetzm at gmx.net
Wed Feb 3 07:20:21 PST 2016


On Tuesday, 2 February 2016 at 21:40:26 UTC, Andrei Alexandrescu 
wrote:
> * call it rcstring or RCString? The first makes it closer to 
> "string", the other is politically correct.

RCString

> * Characters are small so no need to return them by reference. 
> Because of this, making RCString @safe should be possible in 
> current D. However, this also makes RCString not a plug-in 
> replacement for string (which may after all be a good thing)

I assume you also don't want to allow access to the underlying 
storage (most likely `char[]`?). I don't see this as a good thing 
at all. Without the ability of getting at least a `const(char)[]` 
out of it, RCString would be next to useless in practice.

>
> * Since string-compatibility is off the table, how about we fix 
> string's issues with autodecoding? RCString should offer no 
> indexed access and no length. Instead it offers the ranges 
> byCodeUnit, byChar, byWChar, and byDChar. The first one does 
> not do any decoding and offers length and random access. (What 
> should be its element type?) The other ones are bidirectional 
> ranges that do the appropriate decoding.

Definitely. I would prefer this even for normal strings... The 
element type of `byCodeUnit` should be char/wchar/dchar, of 
course.

>
> * Immutable does not play well with reference counting. I'm of 
> a mind to reject immutable rcstring for now and figure out 
> later how to go about it. Then const rcstring is okay because 
> we always consider const a view on mutable strings (even though 
> they're gone). We'll cast const away when manipulating the 
> refcount.

As noted by others, this is not a good idea. We can't solve this 
recurring problem by ignoring it.


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