On 05/09/12 21:13, Patrick Walton wrote:
On 9/5/12 1:10 PM, Gareth Smith wrote:
How about having str be represented internally - but not in the type
system - as a pointer to the actual string data. Copying a str would
copy the pointed-to string data in addition to the pointer, so str would
not be implicitly copyable.
Where would the contents be stored?
On the the non-task-local (AKA shared?) heap.
Graydon wrote:
>> Is this actually a reasonable system?
> That's what they used to be. People passed them by-value too much and
we made too many copies, and balked at the double-indirection implied by
passing around an &str or such.
I was one of those passing them by value too much. I did it because it
seemed like the idiomatic thing to do. Even rustc did it - that made it
seem legit. It no longer seems like the idiomatic thing to do because
the compiler emits a warning about it unless it is done explicitly, so I
try to avoid it. I think that documentation and compiler warnings will
determine typical use.
> That also doesn't handle the fixed-size, constant-memory and
substring-slice use-cases.
Fair enough.
> The current scheme is a very delicate balance between a large number
of pressures; I think it's about the best we're going to get.
The problem with rust's strings is that any rust program I write seems
to be more complicated because of features that strings have that 99% of
the time I will not use. I have to pay for safe concurrency even though
it looks like I will barely be using it. Ditto with fixed size and
constant memory strings.
You created a nice language for programs that are mostly non-concurrent
(regardless of how nice it is for highly concurrent programs), so I and
others are going to try using it for that :) ... and sometimes wondering
why the strings are so hard to use.
I don't know what the fix is, but I think this issue is going to keep
coming up, because I think *for some people* there is a better balance
to be had.
Thanks
Gareth
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