bug#41890: 28.0.50; [PATCH]: Add bindings for project.el

[Juri Linkov]

>>    It turned out that the transient map approach didn't work, as it
>>    ignored the value in default-directory, thus running all commands in
>>    whatever the current project was.
>> Maybe the same function can set default-directory
>> to solve the problem to be able to use set-transient-map?
>
> I think I can explain that: you can set the transient map to handle the
> next command, but you can let-bind a variable to only have the binding 
> have the effect during the next command.
>
> And you can't exactly setq that value either, or else it would overwrite
> the buffer-local default-directory value in the current buffer.

project-switch-project could set a new global variable
project-default-directory and project commands could use it.