emacs: load-path and require (cannot open load file) - emacs

I've got "Cannot open load file" error at (require 'org-mime) while load-path variable seems to be all right:
load-path is a variable defined in `C source code'.
Its value is
("/home/alexey/.emacs.d/elpa/bbdb-20130526.1945" "/home/alexey/.emacs.d/elpa/org-mime-20120112" "/home/alexey/.emacs.d/elpa/smex-20130421.2153" "/usr/share/emacs/24.3/site-lisp" "/usr/share/emacs/site-lisp" "/usr/share/emacs/24.3/lisp
...
Curiously, the remedy looks like this (.emacs):
(add-to-list 'load-path "~/.emacs.d/elpa/org-mime-20120112")
It isn't merely ugly: it's dysfunctional, because the versioned path is subject to change. But why the error?

There is an interesting issue that happens when you load a file that requires another file -- the file that is required must be loaded in chronological order before the next file. For example, if B requires A then A must be placed higher up in chronological order so that when B loads, A is already loaded.
I've had really good luck with this type of setup. Most files end with el or elc, so I'm not sure why you want to load a file with a different or no extension, but it is certainly possible to do that if you want.
(let* ((root.d "~/") (sub-dir (concat root.d ".emacs.d/")))
(load-file (concat sub-dir "init.el"))
(setq load-path
(append `(,root.d ,sub-dir
,(concat sub-dir "elpa/yasnippet")
) load-path)))

Related

"Cannot open load file" error when loading autoload file

I have a file functions called "myloaddefs.el". It has magic coments and forms under them just like the one below.
;;;###autoload
(defun an-awesome-function '()
(interactive)
"A descriptive comment." t)
;;; other descriptive comments and forms...
It's full path is ~/.emacs.d/core/myloaddefs.el.
I also have an autoloads file whose full path is ~/.emacs.d/.local/autoloads.el. I store its path in the variable my-autoload-file.
Before calling update-file-autoloads, my-autoload-file only has an empty comment ;; (making sure it's non-empty to avoid an error). Calling update-file-autoloads as I do below returns nil. And it when I check the my-autoload-file it was indeed updated with autoloads. Loading the 'my-autoload-filereturnst` and also seems successful.
(update-file-autoloads (concat my-core-dir "myloaddefs.el") t my-autoload-file) ; => nil
(load-file my-autoload-file) ; => t
However after calling an autoloaded interactive function with, M-x an-awesome-function I get "Cannot open load file: no such file or directory" "../core/myautoloads". This confuses me greatly because the directory and the file do exist. What could be wrong here?
The path to your autoload file needs to be on your load path since you are using relative paths to load the libraries (eg. ../core/autoloads). I would use expand-file-name anywhere you are creating a path instead of building them using concat.
Try (push (expand-file-name ".local" "~") load-path) prior to calling an-awesome-function (whose definition is incorrect).

How do I get the path from which init.el was loaded?

I am looking to create a custom config for emacs to use for Erlang work and I want to refer to my custom EDTS repo as being under the directory from which init.el was loaded. Right now I have this:
(add-to-list 'load-path "~/.emacs-edts/edts/")
But I would rather not hardcode it and refer to it by variable.
Suggestions?
Strictly speaking the answer is (file-name-directory user-init-file), but instead see C-hv user-emacs-directory
I have the following snippet in my init.el:
(setq my-init-dir
(file-name-directory
(or load-file-name (buffer-file-name))))
This has the advantage of working whether init.el is in your emacs.d directory or not.
I have the following in my init file:
(defun my-file-name-basename (s)
"The directory name, without the final part.
For example:
(my-file-name-basename \"alpha/beta/gamma\") => \"alpha/beta\""
(substring (file-name-directory s) 0 -1))
;; Note: Normally, it's not possible to find out the file a specific
;; function is defined in. However, it's possible to save the file
;; name at the time this file was loaded.
(defvar my-load-file-name load-file-name
"The file name of this file.")
(defun my-start-directory (&optional path)
"The root directory that contains this module.
When PATH is specified, return the start directory concatenated with PATH.
Otherwise return the directory with a trailing slash."
;; Note: Try to figure out where we are, so that we can add the
;; subdirectories. `load-file-name' only works when the file is
;; loaded. Picking up the file from the symbol works when this is
;; evaluated later.
(let ((file-name (or my-load-file-name
(symbol-file 'my-start-directory)
;; Default value. (This is used, for example,
;; when using `eval-buffer' or `eval-region'.)
"~/emacs")))
(let ((start (concat (my-file-name-basename
(my-file-name-basename file-name))
"/")))
(if path
(concat start path)
start))))
In addition to finding out where the file containing the above above code is located (which does not have to be the init file), it provides a convenient way to create paths based on it. For example:
(setq custom-file (my-start-directory "init/custom.el"))

Load and evaluate file from .emacs

I work on many different machines and VMs, each of which might have their own needs regarding options for .emacs. I have a Git repository / subdirectory .common-system with a second Emacs Lisp file .common-system/emacs containing common definitions used for all my systems.
What changes can I make to .emacs which will load and eval my secondary definition file automagically? Bonus points for keeping the secondary file out of my buffer list after startup.
Have you tried:
(load-file ".common-system/emacs")
It works better (as Stefan suggests) if you specify the full path to the file, something like
(load-file "~/.common-system/emacs")
If you stick with you current repository layout, using load-file (as suggested by others) is the way to go.
However, if you name your top-level directory .emacs.d and place the file init.el in it, Emacs will find it and run it automatically. That way, you don't have to hand-edit a .emacs file on each system you use.
You use a (cond), dispatching on variables such as user-login-name, system-type and system-name
(cond
((equal user-login-name
"myname")
;; Stuff
)
((equal system-type 'gnu/linux)
(require 'some-file)
;; some-file, could be any file in load-path, named some-file.el, and ending
;; with (provide 'some-file)
))

emacs: open all .txt files in a specific directory in a specific major mode

EDIT: It turns out that the second edit to my .emacs file actually works. (See the comments below this entry.)
I tried a couple of addition to the .emacs to make all txt files opened in emacs use orgmode. They did not work. How can I make it happen?
;;SET EMACS AS DEFAULT MAJOR MODE TO FOR ALL FILES WITH AN UNSPECIFIED MODE
(setq default-major-mode 'org-mode)
;;OPEN ALL TXT FILES IN ORGMODE
(add-to-list 'auto-mode-alist '("\\.txt$" . org-mode))
Additionally:
It would be even better to open only txt files in a certain directory orgmode. Any hint as to how that could be done would also be appreciated.
Another way to do this is using directory-local variables. This is nice because you can put a file in any directory where you want this behavior to engage, and it works recursively in any subdirectories.
Create a file called .dir-locals.el in the desired directory.
Here are the contents:
((nil (eval . (if (string-match ".txt$" (buffer-file-name))(org-mode)))))
Read this like so: for any major-mode (nil), evaluate the following form:
(if .... (org-mode))
The regex in auto-mode-alist could be something more complex, like "^/path/to/.*\\.txt$"
You can implement a hook which verifies the file directory and modifies the buffer mode:
(add-hook 'find-file-hooks
(lambda ()
(let ((file (buffer-file-name)))
(when (and file (equal (file-name-directory file) "c:/temp/"))
(org-mode)))))
As an alternative you can add the mode line in the beginning of your text file. In this case emacs will set the specified mode.
; -*- mode: org;-*-
* header 1
** header 2
I glued together some code from Oleg Pavliv's answer here, and from yibe's at elisp - File extension hook in Emacs - Stack Overflow
(defun use-org-mode-for-dot-txt-files-in-owncloud ()
(when (and (string-match owncloud buffer-file-name)
(string-match "\\.txt\\'" buffer-file-name))
(org-mode)))
(add-hook 'find-file-hook 'use-org-mode-for-dot-txt-files-in-owncloud)
This way, though ownCloud Web and phone apps are currently friendly only with .txt files, from my PC I can use Emacs' Org-mode for them.
(If I set all .txt files to use Org-mode, it breaks todotxt-mode.)
(Note that owncloud is a string variable equal to my ownCloud path.)

How can I check if a file exists using Emacs Lisp?

I would like emacs to mark files that are generated as read-only when they're opened. The part of the puzzle that I'm missing is how to check if a file "exists". I currently have the following:
;;
;; get file extension
;;
(defun get-ext (file-name)
(car (cdr (split-string file-name "\\."))))
;;
;; get the base name of the file
;;
(defun base-name (file-name)
(car (split-string file-name "\\.")))
;;
;; if an 'lzz' file exists for this header, mark it as read only
;;
(defun mark-read-only ()
(if (string= (get-ext (cur-file)) "h")
(if ( ??file-exists??? (concat (base-name (cur-file)) ".lzz") )
(toggle-read-only))))
What can I use for "???file-exists???"?
Once I find this, I'll add "mark-read-only" to the appropriate hook (which I think is the find-file-hook).
BACKGROUND
We use lzz as a code generator to simplify our C/C++ development process. Briefly, lzz takes a single input file (which looks very like C/C++) and generates header and source files as appropriate.
By default, lzz includes #line directives so that the debugger points to the original source and not the generated source, however, to reduce compilation dependencies we normally disable these directives in header files. The result is that when debugging templates or inline functions, the debugger normally points to the generated header file and not the original source file.
This is not a big deal, however, recently I've found that when debugging I'll make a quick modification to the displayed file and then I'll rebuild. Of course this normally means that the change I made disappears because the file I edited is generated and so the changes are "blown away" during the library rebuild.
SOLUTION
Thanks to everyone for their help and comments. A special thanks to cobbal for pointing out the correct function to use.
Here's the resulting code (with updates based on the other comments here too):
(defun cur-file ()
"Return the filename (without directory) of the current buffer"
(file-name-nondirectory (buffer-file-name (current-buffer)))
)
(defun mark-generated-as-read-only ()
"Mark generated source files as read only.
Mark generated files (lzz or gz) read only to avoid accidental updates."
(if
(or (string= (file-name-extension (cur-file)) "h")
(string= (file-name-extension (cur-file)) "cpp"))
(cond
(
(file-exists-p (concat (file-name-sans-extension (cur-file)) ".lzz"))
(toggle-read-only))
(
(file-exists-p (concat (file-name-sans-extension (cur-file)) ".gz") )
(toggle-read-only))
)
)
)
try file-exists-p
"Return t if file filename exists (whether or not you can read it.)".
Note that it's not spesific to files and works for directories too.
Depending on what you need, you might want file-readable-p instead of file-exists-p.
Apropos will only get you so far. Icicles provides apropos completion and progressive completion which let you find help easily for command, function, variable, etc. names that match subparts in an arbitrary order (is it file-exists-p or exists-file-p?).
Use f.el, modern library for file and directory manipulation. You can use f-exists?, f-file?, f-directory? and many other predicates. The library is better than standard functions, because it's every file related function you'll ever need under one namespace.