Re: query-replace-interactive

[Stefan]

> But even in case with the default to repeat the last replacement it is
> possible to use the last search string/regexp as a default value only
> for the sake of making it available by M-n.  But the real default value
> (such as used when the user types RET with empty input) could be
> interpreted as repeating the last replacement, since if the user
> enters empty input, `read-from-minibuffer' returns the empty string,
> not the argument `default-value'.

But as you said regarding the "a -> b" default, "such use of the default
value is non-standard in Emacs".  And more importantly, it's unimportant.
If you want to reuse a previous search string for replacement, just do

        C-s C-s M-%

instead of

        M-% M-n RET

this also has the advantage of being more general, so you can also do
a replacement on the penultimate search string if you want:

        C-s M-p M-p C-s M-%

>>> C-s C-w C-w ... M-%
>> 
>> C-SPC M-f M-f ... M-w M-% C-y

> Yes, currently this is the most convenient method to do that but it
> requires more keystrokes and wastes the kill ring.

For what it's worth, I can also do

   M-% C-w C-w C-w RET

since I've added a C-w binding in minibuffer-local-map that mimics
isearch's C-w.

> There are other cases where making the last search string accessible
> by M-n is useful.  For example, users might want to start replacing
> the current search string from the beginning of the buffer.  To not
> type C-r several times to reach the beginning of the buffer the user
> can type:

> C-s C-w C-w ... RET M-< M-% M-n RET

Why is that better than

        C-s C-w C-w ... RET M-< C-s M-%

> So, in conclusion, I agree that M-% in isearch should not ask for
> the from-string with initial content of the last search string,
> but M-% invoked not from isearch could provide the last search string
> by M-n.

I don't think it's worth the trouble.

>> Obviously, it's not good enough.  But we can easily take out the "read
>> `to'" part of query-replace-read-args.

> Calling `perform-replace' directly is not good because it skips many
> useful things implemented in interactive commands which call it.
> Most useful of them is recently added handling of \, and \# in
> `query-replace-read-args'.

That's exactly what I meant by the "read `to'" part.  We can take it out of
query-replace-read-args and call it explicitly.

>> The point about using perform-replace is that it allows us to obey
>> both isearch-regexp and isearch-word without doing any if-gymnastic.

> Using `isearch-regexp' to call either `query-replace' or
> `query-replace-regexp' is easy.  Using the value of `isearch-word' for
> replacement might be tricky but currently this is possible with the
> prefix argument C-u M-% or C-u C-M-% even in isearch.

And if you call perform-replace it's neither tricky nor requires
remembering any particular C-u combination.


        Stefan