Calling Ediff which ignores whitespaces from VC Dir

Calling Ediff which ignores whitespaces from VC Dir

[Sebastien Vauban]

Hello,

I'm trying to call my version of `vc-diff' from VC Dir. It simply is a wrapper
above `vc-diff' where I enforce the fact that whitespaces must be ignored.

I thought this would make it:

--8<---------------cut here---------------start------------->8---
    ;; hide up-to-date and unregistered files
    (add-hook  'vc-dir-mode-hook
               (lambda ()
                 (define-key vc-dir-mode-map
                   (kbd "E") 'vc-ediff-ignore-whitespace)))

    (defun vc-ediff-ignore-whitespace ()
      "Ignore regions that differ in white space & line breaks only."
      (interactive)
      (let ((ediff-ignore-similar-regions t))
        (vc-ediff)))
--8<---------------cut here---------------end--------------->8---

but I always get the error:

--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (wrong-number-of-arguments (1 . 2) 0)
  vc-ediff()
  (let ((ediff-ignore-similar-regions t)) (vc-ediff))
  vc-ediff-ignore-whitespace(nil t)
  call-interactively(vc-ediff-ignore-whitespace nil nil)
--8<---------------cut here---------------end--------------->8---

which I don't really understand.

With no certainty, I've tried to copy the parameters of `vc-ediff':

--8<---------------cut here---------------start------------->8---
    (defun vc-ediff-ignore-whitespace (historic &optional not-urgent)
      "Ignore regions that differ in white space & line breaks only."
      (interactive (list current-prefix-arg t))
      (let ((ediff-ignore-similar-regions t))
        (vc-ediff historic not-urgent)))
--8<---------------cut here---------------end--------------->8---

then it worked further...

Though, I now have:

    call-interactively: Symbol's value as variable is void:
    ediff-ignore-similar-regions

when pressing `n' to go to the first difference region.

Any help?

Best regards,
  Seb

-- 
Sebastien Vauban

Re: Calling Ediff which ignores whitespaces from VC Dir

[Stefan Monnier]

> Debugger entered--Lisp error: (wrong-number-of-arguments (1 . 2) 0)

0 is the number of args you have provided.  (1 . 2) is the min and max
number of args expected by the function.

> With no certainty, I've tried to copy the parameters of `vc-ediff':

> --8<---------------cut here---------------start------------->8---
>     (defun vc-ediff-ignore-whitespace (historic &optional not-urgent)
>       "Ignore regions that differ in white space & line breaks only."
>       (interactive (list current-prefix-arg t))
>       (let ((ediff-ignore-similar-regions t))
>         (vc-ediff historic not-urgent)))

You could also use (call-interactively 'vc-ediff) instead.

>     call-interactively: Symbol's value as variable is void:
>     ediff-ignore-similar-regions

That's because ediff was (auto)loaded while ediff-ignore-similar-regions
was let-bound.  So at the end of the let, ediff-ignore-similar-regions
was reset to its previous value (i.e. unbound).

That's a long standing problem.  To work around such issues, you want to
explicitly load ediff before doing the let.


        Stefan

Re: Calling Ediff which ignores whitespaces from VC Dir

[Sebastien Vauban]

Stefan Monnier wrote:
>> Debugger entered--Lisp error: (wrong-number-of-arguments (1 . 2) 0)
>
> 0 is the number of args you have provided.  (1 . 2) is the min and max
> number of args expected by the function.
>
>> With no certainty, I've tried to copy the parameters of `vc-ediff':
>
>> --8<---------------cut here---------------start------------->8---
>>     (defun vc-ediff-ignore-whitespace (historic &optional not-urgent)
>>       "Ignore regions that differ in white space & line breaks only."
>>       (interactive (list current-prefix-arg t))
>>       (let ((ediff-ignore-similar-regions t))
>>         (vc-ediff historic not-urgent)))
>
> You could also use (call-interactively 'vc-ediff) instead.

OK, less error-prone (in case arguments to `vc-ediff' would change).

>>     call-interactively: Symbol's value as variable is void:
>>     ediff-ignore-similar-regions
>
> That's because ediff was (auto)loaded while ediff-ignore-similar-regions
> was let-bound.  So at the end of the let, ediff-ignore-similar-regions
> was reset to its previous value (i.e. unbound).
>
> That's a long standing problem.  To work around such issues, you want to
> explicitly load ediff before doing the let.

When you say "load ediff", I assume you mean writing a `require' call, right?
That way, it's not loaded multiple times?

OK. Latest version, then:

--8<---------------cut here---------------start------------->8---
    (defun vc-ediff-ignore-whitespace (historic &optional not-urgent)
      "Ignore regions that differ in white space & line breaks only."
      (interactive (list current-prefix-arg t))
      (require 'ediff)
      (let ((ediff-ignore-similar-regions t))
        (call-interactively 'vc-ediff)))
--8<---------------cut here---------------end--------------->8---

Though there is no error anymore, it does not work: "similar regions" are not
skipped as expected.

Something due to the fact that the variable `ediff-ignore-similar-regions' is
a local one? When checking its value in the Ediff control window, I see it's
nil -- which confirms the fact that the `let' is somehow not "applied"
correctly.

Is there a way to work around this?

Best regards,
  Seb

-- 
Sebastien Vauban

Re: Calling Ediff which ignores whitespaces from VC Dir

[Stefan Monnier]

> When you say "load ediff", I assume you mean writing a `require' call, right?

Right.

> Though there is no error anymore, it does not work: "similar regions" are not
> skipped as expected.
> Something due to the fact that the variable `ediff-ignore-similar-regions' is
> a local one?

No.

> When checking its value in the Ediff control window, I see it's
> nil -- which confirms the fact that the `let' is somehow not "applied"
> correctly.

No, it's simply that by that time, the let has already ended.
The call to `vc-ediff' sets up the various windows/buffers and puts
the buffers in the proper modes, and then returns.


        Stefan