Re: master 6e796b5: Stop project-root from going into infinite recursion

Re: master 6e796b5: Stop project-root from going into infinite recursion

[Stefan Monnier]

> @@ -215,7 +217,9 @@ It usually contains the main build file, dependencies
>  configuration file, etc. Though neither is mandatory.
>  
>  The directory name must be absolute."
> -  (car (project-roots project)))
> +  (if project--within-roots-fallback
> +      (signal 'cl-no-applicable-method (list 'project-root project))
> +    (car (project-roots project))))

I think `cl-call-next-method` is a better choice.


        Stefan

Re: master 6e796b5: Stop project-root from going into infinite recursion

[Dmitry Gutov]

On 17.03.2021 23:33, Stefan Monnier wrote:
> I think `cl-call-next-method` is a better choice.

If you're sure about that.

The idea here was, some prospective backend author might look at the 
error symbol and make a decision on how to fix the problem based on it.

And "you need to implement this method" seems better expressed with "No 
applicable method" rather than with "No next method".

Re: master 6e796b5: Stop project-root from going into infinite recursion

[Stefan Monnier]

>> I think `cl-call-next-method` is a better choice.
> If you're sure about that.
> The idea here was, some prospective backend author might look at the error
> symbol and make a decision on how to fix the problem based on it.
> And "you need to implement this method" seems better expressed with "No
>  applicable method" rather than with "No next method".

I see.  I consider the difference between the two as an error in CLOS,
but I didn't have the courage to remove it in cl-generic.el ;-)

FWIW, you could also get what you want with something like:

    (cl-defgeneric project-root (project)
      "Return root directory of the current project.
    
    It usually contains the main build file, dependencies
    configuration file, etc. Though neither is mandatory.
    
    The directory name must be absolute.")

    (cl-defmethod project-root (project
                                &context (project--within-roots-fallback
                                          (eql nil)))
      (car (project-roots project)))

This way there indeed won't be any applicable method when
project--within-roots-fallback is non-nil ;-)


        Stefan

Re: master 6e796b5: Stop project-root from going into infinite recursion

[Dmitry Gutov]

On 18.03.2021 00:29, Stefan Monnier wrote:
> I see.  I consider the difference between the two as an error in CLOS,
> but I didn't have the courage to remove it in cl-generic.el;-)

I'm no CLOS expect, so I was choosing purely on how the names sound.

> FWIW, you could also get what you want with something like:
> 
>      (cl-defgeneric project-root (project)
>        "Return root directory of the current project.
>      
>      It usually contains the main build file, dependencies
>      configuration file, etc. Though neither is mandatory.
>      
>      The directory name must be absolute.")
> 
>      (cl-defmethod project-root (project
>                                  &context (project--within-roots-fallback
>                                            (eql nil)))
>        (car (project-roots project)))
> 
> This way there indeed won't be any applicable method when
> project--within-roots-fallback is non-nil;-)

That's a neat suggestion, thanks!