blob: 14553c2d5ea3f2df880e8704abd295cf7218f1ed (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
= noflet - Local function decoration =
This is useful for definining functions that overide a base definition
in some way. You get access to the original (before you re-defined it)
function through a different name.
It's useful for things like this:
{{{
(noflet
((find-file-noselect
(file-name)
(if (string-match-p "^#.*" file-name)
(this-fn "/tmp/mytest")
(this-fn file-name)))
(expand-file-name
(file-name &optional thing)
(if (string-match-p "^#.*" file-name)
(concat "/tmp" (file-name-as-directory
(substring file-name 1)))
(funcall this-fn file-name thing))))
(progn
(expand-file-name "#/thing")))
}}}
This specifies that two functions should be overridden:
* {{{find-file-noselect}}} is changed so that if the file-name begins with {{{#}}} a different file-name altogether is opened
* {{{expand-file-name}}} is changed so that if the file-name begins with {{{#}}} it's resolved via {{{/tmp}}}
In both cases {{{this-fn}}} is used to access the original function
definition of these common Emacs functions.
=== Decorating results ===
noflet can also be used to decorate results of course:
{{{
(noflet ((find-file (file-name &optional wildcards)
(let ((result (funcall this-fn file-name wildcards)))
(with-current-buffer result
(setq some-buffer-local "special"))
result)))
(with-current-buffer (find-file "~/some-file")
(message "buffer local var is: %s" some-buffer-local)))
}}}
This overrides {{{find-file}}} to set a local variable. There are
surely better ways to do it than this but it illustrates the point.
|
