Re: beginning-of-defun (again)

[David Kastrup]

Oleh Krehel <address@hidden> writes:

> David Kastrup <address@hidden> writes:
>
>> Oleh Krehel <address@hidden> writes:
>>
>>> Hi Andreas,
>>>
>>> Andreas Röhler <address@hidden> writes:
>>>
>>>> maybe it's time to have a reasonable default-behavior of
>>>> beginning-of-defun in Emacs Lisp.
>>>
>>> I think it works pretty well as is.
>>>
>>>> open-paren-in-column-0-is-defun-start
>>>
>>> It's a strange variable that doesn't seem to do anything.
>>
>> Huh?
>
> Please give an example then. I'm not able to see a difference when it's
> unset.
>
>>> The only relevant setting is 0 or non-zero (the default).
>>
>> Huh?!?  The only relevant settings are nil and non-nil.
>
> The only relevant use is:
>
>   if (!open_paren_in_column_0_is_defun_start)
>     {
>       find_start_value = BEGV;
>       find_start_value_byte = BEGV_BYTE;
>       goto found;
>     }
>
> Note that it's not checked against Qnil. It may be that Qnil is
> conveniently defined to be 0 though, I'm not sure.

open_paren_in_column_0_is_defun_start is a C variable.  You were talking
about open-paren-in-column-0-is-defun-start which is a Lisp variable.
It is defined using DEFVAR_BOOL:

    @code{DEFVAR_BOOL} makes a C variable of type @code{int} visible in
    Lisp with a value that is either @code{t} or @code{nil}.  Note that
    variables defined with @code{DEFVAR_BOOL} are automatically added to
    the list @code{byte-boolean-vars} used by the byte compiler.

>> Speeds up syntax highlighting by giving it anchor points.  If you
>> encounter
>>
>> (
>>
>> in a file, that counts as the start of some list even without looking
>> whether it might be part of something like
>
> I see. I wonder what the speed-up factor is.

Can be significant depending on the file.

> For example in org.el.
>
>>>> A function resp. top-level-form starts if the beginning of a list is
>>>> followed by a respective keyword.
>>>> The list of keywords being customizable seems a plus :)
>>>
>>> There's no reason for a defun to not start on a newline.
>>
>> But there's a reason for non-defuns to start on a newline.
>
> I call these defuns anyway.

Then you should be happy with the default setting.

-- 
David Kastrup