Re: passing data to process sentinel

[Kevin Rodgers <ihs_4664@yahoo.com>]

Gordon Beaton wrote:
> I run tkdiff from emacs to compare the current buffer contents with
> the corresponding saved file. tkdiff needs two filenames, so I start
> by storing the buffer contents to a temporary file created by
> make-temp-file.
> 
> I'd like to be able to pass the name of the temporary file to a
> process sentinel so it can be cleaned up after tkdiff exits, for
> example by attaching the filename to the process object itself where
> it can be retrieved in the sentinel. To me this seems more elegant
> than storing the filename elsewhere and looking it up.
> 
> One solution I'd like to see is something like this, but of course
> neither set-process-sentinel nor the sentinel itself take the
> additional argument:
> 
>   (set-process-sentinel
>     (start-process "tkdiff" nil "tkdiff" (buffer-file-name) temp-file)
>     'my-sentinel temp-file)
> 
>   (defun my-sentinel (process event mydata) 
>     (if (file-exists-p mydata) (delete-file mydata)))
>     
> I was hoping that something like the following might work, but
> temp-file doesn't seem to get bound in the lambda function:
> 
>   (set-process-sentinel
>     (start-process "tkdiff" nil "tkdiff" (buffer-file-name) temp-file)
>     (lambda (process event)
>       (if (file-exists-p temp-file) (delete-file temp-file))))

Backquote is your friend:

   (set-process-sentinel
     (start-process "tkdiff" nil "tkdiff" (buffer-file-name) temp-file)
     `(lambda (process event)
       (if (file-exists-p ,temp-file) (delete-file ,temp-file))))

-- 
Kevin