[Bug-readline] RFE: use of colour with show-all-if-ambiguous

[Richard Neill]

Dear All,

Here's a UI idea for readline, that I think would be helpful.

When a partial completion is shown, denote the remaining, unmatched part 
of the listed elements (from show-all-if-ambiguous) in colour.
This will make visual grep much easier for the user.

Here is an example. On my current system, I have lots of entries in 
/usr/src/linux*:

$ ls -d /usr/src/linux*
/usr/src/linux@  /usr/src/linux-2.6.27.19-1mnb/ 
/usr/src/linux-2.6.27.4-2mnb/  /usr/src/linux-2.6.27.45-1mnb/ 
/usr/src/linux-2.6.33.7-2mnb/  /usr/src/linux-2.6.36.2-2mnb/

If I navigate through them, using tab-completion, I might, for example 
enter:
  $ ls -d /usr/src/linux-2.6.2 [TAB]

and the following is printed:

  linux-2.6.27.19-1mnb/ linux-2.6.27.4-2mnb/  linux-2.6.27.45-1mnb/
  $ ls -d /usr/src/linux-2.6.27.

In this case, it's quite hard to immediately see exactly where I have 
got to within the completion. (in this particular case, the [TAB] got me 
"7.")

What would be really nice is if the printout were to use either colour 
or the terminal's bold font to distinguish the matched and unmatched 
parts. For example, it might print:


 linux-2.6.27.19-1mnb/ linux-2.6.27.4-2mnb/  linux-2.6.27.45-1mnb/
              -------               -------               --------
 $ ls -d /usr/src/linux-2.6.27.


(I've used underlining to denote the part to be coloured)
which would make it really easy for me to see that the next character I 
should enter must be either a 1 or a 4.


This problem isn't serious when tab-completing/navigating through most 
of the unix directory tree (because the files are short, distinct, and 
mainly lower-case letters which are easy to read), but it does become 
ugly when a directory contains a list of long, similarly-named files 
containing mostly numeric/punctuation characters. Another example that 
springs to mind is per-host config-files named for the MAC-addresses of 
the machines.

One way to control the use of colour might be via the environment 
variables, similar to the way "grep" and "ls" use colour highlighting.

I hope that's useful. Thank you for your time.

Regards,

Richard