Re: How to circumvent warning in batch mode

[Andreas Politz]

Kevin Rodgers <kevin.d.rodgers@gmail.com> writes:

> Decebal wrote:
>> I have the following code:
>> emacs -batch -nw --eval='
>>   (let (
>>         (match-length)
>>         (reg-exp "^ +")
>>         (substitute-str "@")
>>         )
>>     (find-file "input")
>>     (goto-char (point-min))
>>     (while (re-search-forward "^ +" nil t)
>>       (setq match-length (- (point) (match-beginning 0)))
>>       (while (> match-length (length substitute-str))
>>         (setq substitute-str (concat substitute-str substitute-str)))
>>       (replace-match (substring substitute-str 0 match-length))
>>     )
>>     (write-file "outputEmacs")
>>   )
>> '
>> I have severall questions about it.
>> The input file is quite big and I get:
>>     File input is large (31MB), really open? (y or n)
>> Is there a way to circumvent this?
>
> let-bind large-file-warning-threshold to nil around the call to find-file.
>
>> Is there a way to do this more efficient? This script needs about 20
>> seconds. When doing it with a Perl script, it takes about 6 seconds.
>
> 1. Put the code in a file (FILE.el) and byte-compile it.  Then instead of
>    --eval 'CODE' on the command line, use --load FILE.elc
>
> 2. It looks like you are doing a lot of unnecessary string allocation with
>    concat and substring:
>

I would suggest removing the body of the while-loop, in order to see if
there is actually a significant amount of time spend there.

Depending on the file, a great deal goes probably into the
initialization of the major-mode.  Maybe you can use
`find-file-literally' or some other means, I don't know.

-ap