Retracing steps with emacs (When programming /exploring)

Question

Often when fixing a bug or implementing a new feature in a code repository, I start off with an investigatory step.

For example, I would have a lead, a word such as "Article" and I would start by grepping the codebase for "Article". Suppose there are 5 files that contain the word. I would open up one of these files with emacs. Reading the file, I would learn that the code in that file is just a "wrapper" function, and the real meat of the work happens in another place (the parent/caller function) This step would repeat for about a dozen times until I found what I'm looking for. Sometimes I don't find what I'm looking for. Sometimes on a 10 step exploration ( 10 files opened up consecutively) I would decide to take 4 steps back, and branch off in another direction/idea.

Four days later I would be in the shower and have a thought flash, and would want to revisit/retrace my steps but the emacs instance has long been killed.

Is bookmarks.el the answer? Or are there better ways to wander down rabbit holes with emacs.

Answer 1

Yes, Emacs bookmarks are a good answer for getting back to places later (and for restoring contexts later).

But that means that you need to create a bookmark, e.g., perhaps guessing that you might want to get back to the current place.

If you use Bookmark+ then you can optionally have Emacs create bookmarks automatically whenever Emacs is idle for a given time period. You might or might not like to turn this on, e.g., when working on some code that you expect you might want to get back to.

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Another part of your question mentions grepping for some code fragment. Another possibility is to try for a better grep search string: one that will avoid just "wrapper" code -- if that's possible.

Or you can maybe try using a different kind of search than just grep (which is line-oriented). For instance, if you use library isearch-prop.el then you can search the zones of text that match a given regexp, using command isearchp-regexp-context-search or isearchp-regexp-context-regexp-search. In other words, don't use individual lines as search contexts; define the contexts to search as the text that matches a regexp. (A similar feature is available with Icicles search.)

Answer 2

You can use M-. to jump to definitions, and M-, to jump back to places you've looked from.

There's M-?, which can be used to find references in a project.

You can also use the mark ring to go back to places you've marked (for instance with C-SPC, or by using isearch) before, but this is limited to a buffer. You can pop the ring with C-u C-SPC. This can be handy, when you need to import something you're about to use before you get back to what you were writing as well.