[O] Re: Using babel to generate a commit log

[Jambunathan K]

Luke Crook <address@hidden> writes:

> I have written the following code that uses the Emacs vc-* commands to 
> generate 
> a commit log. I would like the output of this code to be included when my 
> file 
> is exported.
>
> #+begin_src emacs-lisp :var limit=""
> ;; Most of this code is copied from vc.el vc-print-log
> (when (vc-find-backend-function (vc-backend (buffer-file-name 
> (current-buffer)))
>                                               'print-log)
>       (let* ((limit (if (numberp limit) limit vc-log-show-limit))
>                (vc-fileset (vc-deduce-fileset t)) ;FIXME: Why t? --Stef
>                (backend (car vc-fileset))
>                (files (cadr vc-fileset)))
>         (with-temp-buffer 
>           (vc-call-backend backend
>                              'print-log
>                              files
>                              (current-buffer))
>           (sit-for 5 t)          
>           (buffer-string))))
> #+end_src
>
> What is happening is; 
>
>   1) The code between #+begin_src and #+end_src is exported and not the 
> result 
> of evaluating the code (the commit log).
>   2) I have to add at delay of at least 5 seconds (set-for 5 t) as vc-git 
> calls 
> "git log" as an asynchronous process. If not for the delay then babel 
> immediately returns an empty buffer and the "vc-call-backend" process never 
> completes.
>
> How can I fix (1).
>
> Is there a better way that I can accomplish (2) ?

Quick hints if you are willing to settle for some hacks.

In vc-do-command, you may have to set OKSTATUS to 0. Track
`vc-disable-async-diff' in vc.el and vc-svn.el for possible hints.

,----[ C-h f vc-do-command RET ]
| vc-do-command is an autoloaded Lisp function in `vc-dispatcher.el'.
| 
| (vc-do-command BUFFER OKSTATUS COMMAND FILE-OR-LIST &rest FLAGS)
| 
| Execute a slave command, notifying user and checking for errors.
| Output from COMMAND goes to BUFFER, or the current buffer if
| BUFFER is t.  If the destination buffer is not already current,
| set it up properly and erase it.  The command is considered
| successful if its exit status does not exceed OKSTATUS (if
| OKSTATUS is nil, that means to ignore error status, if it is
| `async', that means not to wait for termination of the
| subprocess; if it is t it means to ignore all execution errors).
| FILE-OR-LIST is the name of a working file; it may be a list of
| files or be nil (to execute commands that don't expect a file
| name or set of files).  If an optional list of FLAGS is present,
| that is inserted into the command line before the filename.
| Return the return value of the slave command in the synchronous
| case, and the process object in the asynchronous case.
| 
| [back]
`----


,----[ C-h v vc-disable-async-diff RET ]
| vc-disable-async-diff is a variable defined in `vc.el'.
| Its value is nil
| 
| Documentation:
| VC sets this to t locally to disable some async diff operations.
| Backends that offer asynchronous diffs should respect this variable
| in their implementation of vc-BACKEND-diff.
| 
| [back]
`----


>
> Thanks,
> -Luke
>
>
>
>

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