[cfe-dev] Dynamic / Last Resort Lookup

[Argyrios Kyrtzidis]

On Feb 1, 2011, at 6:41 AM, Axel Naumann wrote:

> Hi,
> 
> We need to implement something similar to dynamic scopes:
> 
> void f() {
>  File::Open("serialized.data");
>  object->func();
> }
> 
> This will call func() on an object that was retrieved from the file
> serialized.data (all of it happens at runtime).

Cool!

> The part that blocks us
> from implementing it is Sema: all the lookup hooks require a predefined
> set of identifiers.
> 
> Attached patch creates a last resort, dynamic lookup: if that hook
> (implemented by an abstract interface) has been provided, it will get
> its chance to look up a symbol but only if all the other language
> foreseen lookups have failed (i.e. with lowest precedence).
> 
> We believe that the cost for clang is minimal, but for us the benefit
> would be huge. Any chance that I may check it in? Of course better ideas
> and / or suggestions for naming improvements are very welcome :-)

This can have other uses as well, e.g. resolving names even if the header is missing.
This currently will only work for id-expressions, I'm assuming you are planning to handle failed namespace lookups, typename lookups, etc. ?

-Argiris

> 
> Cheers, Axel.
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