Re: [ELPA] New package: listen

[Philip Kaludercic <philipk@posteo.net>]

Adam Porter <adam@alphapapa.net> writes:

> Hi Andreas,
>
> On 2/25/24 08:17, Andreas Schwab wrote:
>> On Feb 25 2024, Adam Porter wrote:
>> 
>>>> @@ -942,10 +941,10 @@ extension.
>>>>      Return one of symbols `vorbis', `opus', `flac', or `mp3'."
>>>>      (let ((case-fold-search t))
>>>> -    (cond ((string-match ".ogg$" filename) 'vorbis)
>>>> -          ((string-match ".opus$" filename) 'opus)
>>>> -          ((string-match ".flac$" filename) 'flac)
>>>> -          ((string-match ".mp3$" filename) 'mp3)
>>>> +    (cond ((string-match ".ogg\\'" filename) 'vorbis)
>>>> +          ((string-match ".opus\\'" filename) 'opus)
>>>> +          ((string-match ".flac\\'" filename) 'flac)
>>>> +          ((string-match ".mp3\\'" filename) 'mp3)
>>>>              (t nil))))
>>>
>>> According to the Elisp manual: "When matching a string instead of a
>>> buffer, ‘$’ matches at the end of the string or before a newline
>>> character."  So it appears to be correct here
>> It should only match at the end of the string, not before a newline.
>
> As the manual says:
>
> ‘$’
>      is similar to ‘^’ but matches only at the end of a line (or the end
>      of the accessible portion of the buffer).  Thus, ‘x+$’ matches a
>      string of one ‘x’ or more at the end of a line.
>
>      When matching a string instead of a buffer, ‘$’ matches at the end
>      of the string or before a newline character.
                     ^
                     this is the problem.

Since it is possible for file-names to contain newline characters,
matching the end of a line can result in false-positives:

(string-match-p
 "\\.el$"
 "foo.el\nbar.le")
;;=> 3

(string-match-p
 "\\.el\\'"
 "foo.el\nbar.le")
;;=> nil

(It's called the "manual", not the "infallible" (hehe) for a reason)

-- 
	Philip Kaludercic on peregrine