Re: Improvement proposals for `completing-read'

[Daniel Mendler <mail@daniel-mendler.de>]

On 4/8/21 8:13 PM, Stefan Monnier wrote:
>> This is similar to what I am doing in my `consult-line` command, which is
>> a Swiper equivalent. There I encode the line number in Unicode characters of
>> some private plane and hide them with 'invisible or 'display.
> 
> I can understand the `invisible` but I would have used plain `%s` or
> `number-to-string` rather than funny unicode chars.

I am using funny unicode tofus in order to prevent accidental matching 
when searching for numbers. The idea is that the numbers should be 
unmatchable!

>> Maybe that's the cleaner solution? The nice advantage is that it would be
>> backward compatible. I could just start to mark my prefixes as 'unmatchable
> 
> Why put it in the prefix rather than the suffix?
> 
>> and the basic completion style would suddenly start to work. On older Emacs
>> versions everything would continue to work as is; the user is required to
>> use a completion style which matches substrings,
> 
> If you put the line numbers in the suffix, then they won't bother
> anyone, even with the most basic completion scheme.

Yes, then it would work with basic completion. The main reason was that 
the candidates are already prefixed with line numbers in the 'display 
property. The real string is the tofu-encoded number hidden behind that.

Maybe it would be better to implement this differently. Use an 
affixation function prefix for the line numbers and append the 
'invisible tofu-encoded line number as suffix. But I think I implemented 
`consult-line` before the affixation function came into existence. I 
have to consider this.

Daniel