Re: How to use display text property with after-string?

[Eli Zaretskii <eliz@gnu.org>]

> From: Marcin Borkowski <mbork@mbork.pl>
> Cc: help-gnu-emacs@gnu.org
> Date: Fri, 21 Oct 2016 21:41:21 +0200
> 
> > The 'display' property doesn't support after-string, only the overlay
> > properties do.
> 
> I see.  I was a bit afraid that is the case.
> 
> Is there any other way to put some nonexistent text in the buffer?

What's wrong with 'display' text property?  Just make its value be a
string, not '(after-string "something").

> Overlays are not very good that, since I hear many overlays in a buffer
> may slow things down.  My use case is as follows: I want to write
> a function which will find all the dates in the US format (M/D/Y) in the
> buffer and put a date in a sane format (maybe together with something
> like "3 days ago" or "tomorrow") next to them.  (That would be very
> useful for me, since I sometimes get emails from Americans, and dealing
> with dates in M/D/Y format is a huge cognitive load for me;-).)

The 'display' text property whose value is a string causes that string
be displayed _instead_ of the text covered by the text property.
Which sounds exactly what you want.  One caveat: you cannot move
cursor through the display string (the same is true for
after-strings).