C-x C-f, Tab (in)completion and visiting the wrong, new files

[David Reitter <david.reitter@gmail.com>]

Does this happen to you, too?

I've got several files in my directory:

foo.tex
foo.aux
foo.pdf
foo.1.tex
bar.txt


To open one, I do

C-x C-f
ba <TAB>
<RET>

and because I'm used to it, I do:

C-x C-f
fo <TAB>
<RET>

What happens then is that only "foo." is in the minibuffer, and a  
buffer visiting the non-existant file of that name is visited.  
Usually that means that I have to kill it and start again, navigating  
to the appropriate file. That is highly annoying.

Of course I could all blame it on myself and bind C-x C-f to `find- 
file-existing'.
But if the same happens to others as well, perhaps a more general  
change could make Emacs more convenient in this respect.

One option would be the following:

Whenever Tab is used to (partially) complete a file name (or even any  
other symbol), we assume that the user wants to input the name of an  
existing file (or element of the completion list). If the file name  
or symbol is incomplete due to an ambiguity, an immediately following  
RET just does `ding'. Otherwise, i.e. a further RET or some editing  
action in the buffer, just exists the minibuffer as before.

I think it is safe to assume the TAB means that a string existing in  
the completion table is to be entered, at least in the case of file  
name completion.