[llvm-commits] [llvm] r148463 - /llvm/trunk/include/llvm/ADT/ArrayRef.h

[Chris Lattner]

On Jan 18, 2012, at 11:01 PM, David Blaikie wrote:
> On Wed, Jan 18, 2012 at 10:34 PM, Chris Lattner <sabre at nondot.org> wrote:
>> URL: http://llvm.org/viewvc/llvm-project?rev=148463&view=rev
>> Log:
>> Introduce a new MutableArrayRef class, which refers to a series of mutable
>> T's that are consequtively in memory.
> 
> Just forwarding a brief discussion I had with Chris on IRC for the
> email record - I'm pretty sure this could be implemented by switching
> things around & migrating existing ArrayRef<T> code to ArrayRef<const
> T> (& making his MutableArrayRef be the basic/generic ArrayRef
> template and partially specializing ArrayRef<const T> using the old
> ArrayRef implementation). Just thought I'd mention this in case anyone
> else had a similar thought.

Hi David,

After having thought about this a bit, I'm not sure this is a good thing to do.

By *far* the common case is than non-mutable array-ref version: punishing all clients to have to plop in a const seems really unfortunate, and your diff shows some massive code thrash that this causes.  I think that forcing the unusual case to spell out MutableArrayRef is actually a good thing, because it makes things very explicit.

-Chris