Re: Subprojects in project.el

[João Távora]

Dmitry Gutov <dgutov@yandex.ru> writes:

> What do you mean, without breaking compatibility? Adding a new
> required argument means it will break any Lisp code that calls this
> function.

The example I gave you was for a function explicitly marked "interactive
only", so it's not a problem.  In fact all these functions should be
"interactive only".  But in other cases, make that argument optional.

> And it's probably not that big a deal if we had no other choice, but
> we do. Update the commands to call a different new function. 

As I explain below, you'll be littering the code with non-idiomatic
Elisp.  

> That will actually require *fewer* changes, as you might have noticed
> now.

Not sure about that.

> diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
> index c1245704bcc..9e5fcfe0b06 100644
> --- a/lisp/progmodes/project.el
> +++ b/lisp/progmodes/project.el
> @@ -1139,6 +1139,19 @@ project-prefixed-buffer-name
>            (downcase mode)
>            "*"))
>
> +(defun project-parent (project)
> +  (project-current nil (file-name-as-directory
> +                        (file-name-directory
> +                         (directory-file-name (project-root project))))))
> +
> +(defun project-current-or-parent (lookup-parent)
> +  (let ((project (project-current t)))
> +    (when lookup-parent
> +      (setq project (project-parent project)))
> +    (unless project
> +      (user-error "No parent project"))
> +    project))
> +
>  (defcustom project-compilation-buffer-name-function nil
>    "Function to compute the name of a project compilation buffer.
>  If non-nil, it overrides `compilation-buffer-name-function' for
> @@ -1155,7 +1168,8 @@ project-compile
>    "Run `compile' in the project root."
>    (declare (interactive-only compile))
>    (interactive)
> -  (let ((default-directory (project-root (project-current t)))
> +  (let ((default-directory (project-root (project-current-or-parent
> +                                          (eq current-prefix-arg '-))))
>          (compilation-buffer-name-function
>           (or project-compilation-buffer-name-function
>               compilation-buffer-name-function)))

Sounds more complicated that it needs to be, and no reason why
project-current-or-parent shouldn't be just project-current, with
another optional argument at most.

Anyway my idea to add PROJECT is nothing exotic: it's the standard
idiomatic Elisp solution used in such basic functionality as M-x
display-buffer, find-file, etc.  There's no reason to stray from that.

João