[Mono-dev] [Dotnet-runtime-dev] ASCII Strings Proposal

Jonathan Gilbert logic at deltaq.org
Thu Jul 28 07:15:55 UTC 2016

Phew :-) I must have gotten the wrong idea from this:


Jonathan Gilbert

On Thu, Jul 28, 2016 at 12:06 AM, Miguel de Icaza <miguel.de.icaza at gmail.com
> wrote:

> Hello Jonathan,
> I personally think it is a terrible idea to make Mono completely unable to
> run code that compiles and runs just fine on Microsoft's .NET framework.
> Could get_OffsetToStringData be made to convert the ASCII representation
> back to UCS-2 on-the-fly for that edge case where the code actually uses
> the fixed (char *ptr = str) pattern? It's not a very common pattern, so
> the overhead of the conversion, while defeating the purpose of using that
> pattern in the first place, would affect only the tiniest minority of code.
> If this were to become a standard part of Mono, that would have to be done.
> The reason it is not done in the current patch is that we needed to
> identify all the spots with issues so they could adjusted to deal with the
> two encodings, purely a bootstrapping side effect.
> And we need the spots adjusted, so we do not needlessly create duplicate
> strings on demand, otherwise one of the benefits of this work (reduce
> memory pressure) would go out the window.
> If this were the direction taken, it might be nice also to provide a way
> to force an ASCII-capable string to be UCS-2 anyway, in case there are
> people who want the fixed (char *ptr = str) pattern to remain performant
> -- perhaps an environment variable?? Obviously we wouldn't want the Mono
> runtime to scan the environment block every time it allocates a string, so
> perhaps it could do the check & cache the result once on startup, and then
> allow some innocuous method that's already doing a lot of work, such as
> string.IsInterned, to re-check it. This avoids adding Mono-specific API,
> so that code written to be aware of Mono's peculiarity still runs just fine
> on other frameworks.
> Something like that.
> Miguel.
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