Re: How to reliably edit a file from within Emacs Lisp and return a string?

[Jean Louis]

* Eli Zaretskii <eliz@gnu.org> [2019-08-23 16:28]:
> See, that's exactly the paradigm I suggest to unlearn when you
> implement features, such as the one you described, entirely in
> Emacs.  What you need instead is to trigger something (which I don't
> yet think I understand) once editing is complete.  Can you describe
> in more detail what should your feature do after the user is done
> with editing the file?

Thanks for helping. I am reading string from PostgreSQL database
field. And I wish to edit that string. It is best done if string is
first written into the file, so that I can edit the file, and after
killing the buffer to read the string from file, so that it can be fed
into the database.

Question is basically how to know, from Emacs Lisp, reliably, that
process of editing of a buffer finished, so that string can be read
from file, thereafter.

I feel solution is very simple, I just don't know it.

Jean