Re: [Patch] Add project.el command to replace symbol at point throughout project

[Dmitry Gutov]

On 12.01.2022 21:56, Juri Linkov wrote:
> > > > If we're trying to improve project-query-replace-regexp, why not make it
> > > > use the symbol at point by default?
> > > I thought about the option of using symbol at point by default, but
> > > I noticed that the command currently uses the history
> > > variable. I wondered if some people were relying on its current behavior
> > > in a way that I didn’t anticipate (especially since I’m pretty new to all
> > > this). If so, it would be an annoying change to have to worry about
> > > whether the cursor is on a symbol when using a command you previously
> > > relied on. I wanted to try to put forth something possibly useful without
> > > breaking stuff.
> > >
> > > > You would use the same command, but would be able to press RET to have
> > > > the default regexp (symbol at point) used as FROM. I don't have a patch
> > > > yet, but it might be something that all callers of
> > > > query-replace-read-args might benefit from.
> > > Since I think I can understand what you’re suggesting, I would be happy
> > > to make an attempt at a patch to modify the callers of
> > > query-replace-read-args to default to a regexp quoted
> > > symbol-at-point. But no worries if you would rather have experienced eyes
> > > on it.
> >
> > I'm actually not sure about the best way to implement this: whether we
> > definitely want query-replace-read-args to use symbol-at-point as the
> > default FROM. But it does sounds handy to me. Let's ask the developer who
> > touched it last.
>
> query-replace-read-args can't be changed because in query-replace
> RET should use the previous from->to pair from the history.

That probably makes sense. But the user could use 'M-p' for that and 
otherwise enjoy a different default (FROM defaulting to symbol-at-point).

But it would be a breaking change, admittedly.

> So if you want, you could change project-query-replace-regexp:
> let-bind read-regexp-defaults-function around the call
> of query-replace-read-args, and use a symbol at point as the default.

...or that. After all, when doing project-wise replacements, you 
probably wouldn't repeat the same search twice. Or at least, not do it 
often.

> > > > And you can actually do this right now:
> > > >
> > > > - Enter command 'project-query-replace-regexp'
> > > > - Press M-n, having the symbol at point picked up as FROM, hit return
> > > > - Enter the replacement string and hit return
> > > This is awesome! Did not know about that behavior, thank you for sharing!
> >
> > That capability actually comes with the "forward history" thing. Not very
> > obvious, but when you learn about it, it's pretty nice.
>
> Maybe the prompt should show some indication that the default
> can be fetched by M-n?

Could be an improvement, but I'm not sure how that'd look, or what text 
to show ("future history" is not a very obvious name).