Isearch vs Ctrlf Mode

isearch is the basic search command built into Emacs. The "i" stands for "incremental"; it starts searching as soon as you start typing, and refines the search term as you keep typing. There are also commands to search based on where your cursor starts out: to search for occurences of the term under the cursor, to gradually add successive words to the search term, etc. You initiate a search with control-s, and successive control-s while searching jump to successive matches of the term.

A few subtle operational points make it a natural navigational aid:

• if you hit ENTER your cursor is left at the current term, otherwise if you quit by control-g it returns the cursor back to where you started, and

• when you start a search, the mark is left at the start-point.

My workflow then typically looks like:

• start a search with control-s

• Let's assume I'm looking for some function, or want a quick reminder of what I've defined, so I search for "defun"

• I keep hitting control-s, quickly looking at each one

• Then:

  • If I've seen enough, I quit with control-g and I'm back where I was.

  • If I want a more in-depth look, I stop searching with ENTER. When I'm finished, I can invoke control-SPACE to jump back to where I was.

That all works great, and is so hard-wired that I don't even notice the little inconsistences or iritations around the process! The big one is: it actually takes you outside of "Emacs" mode in a way. That is to say, once you start searching, you can't use your normal editing commands to edit the search term.

For example, say I start searching for the string "save", but quickly realise that there's a lot of these that I'm not interested in, so I control-a in order to go to the start of my term and refine it to eg "_save".

This does not do what you expect! It actually quits your current search, and jumps to the beginning of whichever line the cursor was currently on. In other words, isearch-mode displays your term in the minibuffer, but you can't otherwise operate on it as you normally would.

Most of the time I bump into this accidentally, curse and start again.

Others with more agency over their environment did not accept the status-quo however, and there is now a competing ctrlf-mode. This works much the same as isearch, but actually feels like more of a first-class citizen of Emacs, because all your normal editing commands operate as they should on your search term. When I grokked this, I immediately switched.

Strangely, the swiitch didn't take and I've now reverted back to vanilla isearch, paper-cuts and all. Why?

My chief problem is that my isearch workflow has accreted several extensions over the years, which seemed to be incompatible with ctrlf-mode, and to boot the nicer aspects of isearch aren't replicated.

• The ability to add words (or characters, etc) is missing. I realised I used these way more than I might have realised!

• Because ctrlf-mode does actually use the minibuffer, it's possibly harder to jump into other "modal" commands from it¹. I use two such examples in my regular workflow:

  • Start searching, then use control-' to immediately jump to my desired location via avy-isearch

  • Start searching, then hit meta-i to switch to consult-line for an overview that I can fuzzily refine (ctrlf-mode does let you switch to occur-mode, but this isn't as interactive).

Added up, I found I wasn't gaining enough benefit from the improvements of ctrlf-mode to warrant keeping it — so, I finally went looking for "how to edit the isearch search-term": low and behold, it's entirely possible and just needs to be invoked with the command M-e! Just hit control-s again, or ENTER, and you're back to searching — not quite as smooth, but given the other benefits above, more than enough for me.