> Date: Mon, 31 Oct 2011 15:28:22 -0400 > From: Eric Roode <sdn.gn...@mailnull.com> > > I would like new buffers to default to utf-8 encoding, and I would like > indeterminate files (like text files, especially source code files) also to > use utf-8, unless the -*- line specifies a different coding system.
What for? What you ask for doesn't make sense without some explanation. It is meaningless to say that pure ASCII files should have UTF-8 encoding, because UTF-8 is indistinguishable from ASCII when all the characters are 7-bit ASCII. > By default, when I create a new buffer that isn't associated with any file, > the coding system is set to 'iso-latin1-dos'. When I visit an existing > (text) file, its coding system is set to 'undecided-dos'. > > I tried to change this by executing > (prefer-coding-system 'utf-8) > After that, when I create a new file, the coding system in the new buffer > is set to 'utf-8'. As expected. I presume this accomplishes part of what you wanted. > However, when I open an existing file, emacs still sets its coding > system to 'undecided-dos'. If the file includes only 7-bit ASCII, this is also expected behavior. Please explain why you aren't happy with this. > Digging further, it seems that this is controlled by the variable > file-coding-system-alist. If a file name does not match any of the > patterns in that list, the function find-buffer-file-type-coding-system (in > dos-w32.el) is invoked to determine what coding system to use for the file. > > That function *always* returns 'undecided' for text files, or > 'no-conversion' for files it determines are binary. The only time it uses > the default value for buffer-file-coding-system is if the file doesn't yet > exist! That is how Emacs behaves on all platforms, even on Unix. The default value of buffer-file-coding-system is used only for non-existing files or for buffers not related to files. When a buffer visits an existing file, Emacs always sets its encoding to match the encoding of the file. prefer-coding-system just tells Emacs which encoding to prefer when more than one can match the encoding of an existing file. > Am I reading this right? There is no way to set a preferred coding system > for existing files under Windows? There _is_ a way, but it doesn't do what you expect. Please explain why your expectations are different, and in particular what is wrong with the current behavior in your use cases. > 'prefer-coding-system' only works in *nix environments? No, it works the same on all platforms. The Windows implementation has a few subtle points, but it doesn't change the basic behavior. > I have to either add every source and text file name > pattern to file-coding-system-alist, or manually change the buffer coding > every time I visit an existing file? You don't and you shouldn't. It is meaningless to change buffer coding after you visit a file, except when you save the file. After telling Emacs to prefer UTF-8, as you did, whenever Emacs needs to encode a file when you save it, it will use UTF-8 if possible, and if not, it will ask you for a different encoding. Again, if this is not what you want, please explain why.
