MI fine-grained versioning

[Bob Rossi]

On Mon, Dec 18, 2006 at 06:35:33PM +0300, Vladimir Prus wrote:
> 
> At the moment, MI does not have any mechanism to announce supported
> features. For example, I have a patch to add "frozen" variable objects. To support
> such feature in a backward-compatible fashion, the frontend must know if that
> features is supported by the given gdb binary.
> 
> Using version number is not very reliable -- for example if you use the CVS state
> of gdb, the version number is not yet bumped.
> 
> Yet another approach is to "detect" presence of feature by trying some commands,
> or by trying commands with some new options, or by constructing more contrived test
> cases. However that's troublesome.
> 
> How about adding new MI command that returnes list of supported fine-grained features.
> For example:
> 
> 	-list-features
> 	^done,result=["frozen_variables","info_path_expression"]
> 
> The MI manual would contain a section listing all feature names and briefly documenting them.

Great idea!

There are a few gothcha's. For instance, each command can support
several parameters, so you might want to report on that. But more
tricky, is when a command adds an output field that the front end cares
about. An example of this would be that the -break-list command has
always existed, but the -break-list command added fullpath functionality
later on it it's life. How would you handle this, if at all?

Thanks,
Bob Rossi