Mixing
Compare if the file content is changed on the buffer
Clash Royale CLAN TAG#URR8PPP
up vote
1
down vote
favorite
I want to do something like if the "buffer-changed" but "content-not-changed", reverted the buffer.
When I work on the checking if the content changed, I tested the following code, but it can't work, it always return nil even if I just save the buffer.
(defun file-content-keep-same(BUFFER)
(interactive)
(save-restriction
(widen)
(let ((original-buffer BUFFER)
(original-size (buffer-size BUFFER))
(filename-on-disk (buffer-file-name (current-buffer))))
(message "buffer size %d" original-size)
(with-temp-buffer
(insert-file-contents filename-on-disk)
(message "%s %d" filename-on-disk (point-max))
(zerop
(compare-buffer-substrings original-buffer 1 original-size
(current-buffer) 1 (point-max))))
)
))
where is it wrong for above code?
buffers
asked Aug 29 at 2:46
zhihuifan
1084
add a comment |Â
up vote
1
down vote
favorite
I want to do something like if the "buffer-changed" but "content-not-changed", reverted the buffer.
When I work on the checking if the content changed, I tested the following code, but it can't work, it always return nil even if I just save the buffer.
(defun file-content-keep-same(BUFFER)
(interactive)
(save-restriction
(widen)
(let ((original-buffer BUFFER)
(original-size (buffer-size BUFFER))
(filename-on-disk (buffer-file-name (current-buffer))))
(message "buffer size %d" original-size)
(with-temp-buffer
(insert-file-contents filename-on-disk)
(message "%s %d" filename-on-disk (point-max))
(zerop
(compare-buffer-substrings original-buffer 1 original-size
(current-buffer) 1 (point-max))))
)
))
where is it wrong for above code?
buffers
asked Aug 29 at 2:46
zhihuifan
1084
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I want to do something like if the "buffer-changed" but "content-not-changed", reverted the buffer.
When I work on the checking if the content changed, I tested the following code, but it can't work, it always return nil even if I just save the buffer.
(defun file-content-keep-same(BUFFER)
(interactive)
(save-restriction
(widen)
(let ((original-buffer BUFFER)
(original-size (buffer-size BUFFER))
(filename-on-disk (buffer-file-name (current-buffer))))
(message "buffer size %d" original-size)
(with-temp-buffer
(insert-file-contents filename-on-disk)
(message "%s %d" filename-on-disk (point-max))
(zerop
(compare-buffer-substrings original-buffer 1 original-size
(current-buffer) 1 (point-max))))
)
))
where is it wrong for above code?
buffers
asked Aug 29 at 2:46
zhihuifan
1084
I want to do something like if the "buffer-changed" but "content-not-changed", reverted the buffer.
When I work on the checking if the content changed, I tested the following code, but it can't work, it always return nil even if I just save the buffer.
(defun file-content-keep-same(BUFFER)
(interactive)
(save-restriction
(widen)
(let ((original-buffer BUFFER)
(original-size (buffer-size BUFFER))
(filename-on-disk (buffer-file-name (current-buffer))))
(message "buffer size %d" original-size)
(with-temp-buffer
(insert-file-contents filename-on-disk)
(message "%s %d" filename-on-disk (point-max))
(zerop
(compare-buffer-substrings original-buffer 1 original-size
(current-buffer) 1 (point-max))))
)
))
where is it wrong for above code?
buffers
asked Aug 29 at 2:46
zhihuifan
1084
edited Aug 29 at 2:58
asked Aug 29 at 2:46
zhihuifan
1084
asked Aug 29 at 2:46
zhihuifan
1084
asked Aug 29 at 2:46
zhihuifan
1084
1084
add a comment |Â
add a comment |Â
1 Answer
1
active
oldest
votes
up vote
3
down vote
accepted
where is it wrong for above code?
(buffer-size) ≠(point-max), your use of compare-buffer-substrings is incorrect. A better idea is omitting the START1/END1/START2/END2 argument by supplying nil, then (point-min) and (point-max) will be used automatically in corresponding buffers.
Here is my attempt (for code simplicity, it doesn't take account of narrowing)
(defun same-buffer-file-p (buffer file)
"Return t if BUFFER and FILE have the same contents."
(with-temp-buffer
(insert-file-contents file)
(zerop
(let ((case-fold-search nil))
(compare-buffer-substrings buffer nil nil
(current-buffer) nil nil)))))
;;; Tests
(write-region "hello" nil "hello.txt")
(with-temp-buffer
(insert "hello")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => t
(with-temp-buffer
(insert "HELLO")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => nil
By the way, Emacs already provides similar feature in C-x s (save-some-buffers) then d (or simply M-x diff-buffer-with-file).
answered Aug 29 at 5:08
xuchunyang
7,3491823
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
accepted
where is it wrong for above code?
(buffer-size) ≠(point-max), your use of compare-buffer-substrings is incorrect. A better idea is omitting the START1/END1/START2/END2 argument by supplying nil, then (point-min) and (point-max) will be used automatically in corresponding buffers.
Here is my attempt (for code simplicity, it doesn't take account of narrowing)
(defun same-buffer-file-p (buffer file)
"Return t if BUFFER and FILE have the same contents."
(with-temp-buffer
(insert-file-contents file)
(zerop
(let ((case-fold-search nil))
(compare-buffer-substrings buffer nil nil
(current-buffer) nil nil)))))
;;; Tests
(write-region "hello" nil "hello.txt")
(with-temp-buffer
(insert "hello")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => t
(with-temp-buffer
(insert "HELLO")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => nil
By the way, Emacs already provides similar feature in C-x s (save-some-buffers) then d (or simply M-x diff-buffer-with-file).
answered Aug 29 at 5:08
xuchunyang
7,3491823
add a comment |Â
up vote
3
down vote
accepted
where is it wrong for above code?
(buffer-size) ≠(point-max), your use of compare-buffer-substrings is incorrect. A better idea is omitting the START1/END1/START2/END2 argument by supplying nil, then (point-min) and (point-max) will be used automatically in corresponding buffers.
Here is my attempt (for code simplicity, it doesn't take account of narrowing)
(defun same-buffer-file-p (buffer file)
"Return t if BUFFER and FILE have the same contents."
(with-temp-buffer
(insert-file-contents file)
(zerop
(let ((case-fold-search nil))
(compare-buffer-substrings buffer nil nil
(current-buffer) nil nil)))))
;;; Tests
(write-region "hello" nil "hello.txt")
(with-temp-buffer
(insert "hello")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => t
(with-temp-buffer
(insert "HELLO")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => nil
By the way, Emacs already provides similar feature in C-x s (save-some-buffers) then d (or simply M-x diff-buffer-with-file).
answered Aug 29 at 5:08
xuchunyang
7,3491823
add a comment |Â
up vote
3
down vote
accepted
up vote
3
down vote
accepted
where is it wrong for above code?
(buffer-size) ≠(point-max), your use of compare-buffer-substrings is incorrect. A better idea is omitting the START1/END1/START2/END2 argument by supplying nil, then (point-min) and (point-max) will be used automatically in corresponding buffers.
Here is my attempt (for code simplicity, it doesn't take account of narrowing)
(defun same-buffer-file-p (buffer file)
"Return t if BUFFER and FILE have the same contents."
(with-temp-buffer
(insert-file-contents file)
(zerop
(let ((case-fold-search nil))
(compare-buffer-substrings buffer nil nil
(current-buffer) nil nil)))))
;;; Tests
(write-region "hello" nil "hello.txt")
(with-temp-buffer
(insert "hello")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => t
(with-temp-buffer
(insert "HELLO")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => nil
By the way, Emacs already provides similar feature in C-x s (save-some-buffers) then d (or simply M-x diff-buffer-with-file).
answered Aug 29 at 5:08
xuchunyang
7,3491823
where is it wrong for above code?
(buffer-size) ≠(point-max), your use of compare-buffer-substrings is incorrect. A better idea is omitting the START1/END1/START2/END2 argument by supplying nil, then (point-min) and (point-max) will be used automatically in corresponding buffers.
Here is my attempt (for code simplicity, it doesn't take account of narrowing)
(defun same-buffer-file-p (buffer file)
"Return t if BUFFER and FILE have the same contents."
(with-temp-buffer
(insert-file-contents file)
(zerop
(let ((case-fold-search nil))
(compare-buffer-substrings buffer nil nil
(current-buffer) nil nil)))))
;;; Tests
(write-region "hello" nil "hello.txt")
(with-temp-buffer
(insert "hello")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => t
(with-temp-buffer
(insert "HELLO")
(same-buffer-file-p (current-buffer) "hello.txt"))
;; => nil
By the way, Emacs already provides similar feature in C-x s (save-some-buffers) then d (or simply M-x diff-buffer-with-file).
answered Aug 29 at 5:08
xuchunyang
7,3491823
answered Aug 29 at 5:08
xuchunyang
7,3491823
answered Aug 29 at 5:08
xuchunyang
7,3491823
answered Aug 29 at 5:08
xuchunyang
7,3491823
7,3491823
add a comment |Â
add a comment |Â
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