bug#2042: Ido-mode : filtering does not keep ordering

[Leo <sdl.web@gmail.com>]

On 2011-10-02 03:10 +0800, Chong Yidong wrote:
> Leo <sdl.web@gmail.com> writes:
>
>> I occasionally try iswitch-mode and find its buffer switching much
>> more pleasant to use than ido's. The trouble is ido tries to be smart
>> in ordering matches. Sadly that gets in the way most of the time.
>
> Could you explain in words what the existing code tries to do?
>
> Maybe it's indeed misguided and ought to be taken out, but it would be
> good to first figure out what the original intention was.

The existing code gives different precedence to different match type:

 full-matches > suffix matches > prefix matches > remaining matches

For example in switching buffers in ido:

input: ab

Buffer: ab[c]{abcd | abc | xabcd | xabc}

now when the user types c, it changes to:

Buffer: abc{abc | abcd | xabcd | xabc}

Note the different ordering of "abcd" and "abc". Because typing is so
much quicker than observing the new order, one usually mis-chooses a
match.

Thus, the above strategy may break down when the original ordering is
meaningful for example, (buffer-list) returns a list in order of
recency.

Leo