Irreal

Marcin Borkowski, mbork, posted a handy snippet of Elisp to automatically create parent directories if they don’t already exist. It’s similar to mkdir -p in that if intermediate directories don’t already exist they are created for you.

That turns out to be easy because the Elisp function make-directory will do this if the second argument is non-nil. All you need do add a hook function to find-file-not-found-functions that calls make-directory with the required non-nil second argument. See mbork’s post for an example of the simple code needed to do this.

Abo-abo has a post on swiper-all that everyone using swiper should read. It turns out that there’s a command called swiper-all that will perform the swiper search on all opened buffers. That is, on all buffers associated with a file. That’s a tremendously useful facility and if you have swiper installed you already have it. You can call it with 【Meta+x】 swiper-all or, if you think you’ll use it a lot, you can bind it to a key sequence.

If you aren’t a swiper user, take a look at Mike Zamansky’s video on searching with swiper to see how it works. You can also check out the swiper GitHub site and the documentation. I’ve been using it for about a month and really like it. Discovering swiper-all just makes it better.

Wilfred Hughes has contributed a cute and potentially useful package that he calls suggest. The idea is that you’re looking for an Elisp function to perform a particular calculation or transformation but don’t know the function’s name. Suggest asks you for an input and the desired output and then suggests functions to accomplish that.

One example that Hughes offers is: given

2
2

with the desired output of

4

suggest offers

(+ 2 2)
(* 2 2)
(expt 2 2)

That’s pretty neat and almost seems like magic but really amounts to taking a list of functions and applying each one to the input(s) to see if it yields the desired result. Despite the brute force, Hughes says it almost always yields an immediate result.

There’s a bit more than just trying every function available though. For example, you have to be careful about side effects. As Hughes says, you don’t won’t to delete a file as a side effect when you’re testing prospective functions. Hughes has a curated list of functions that seems to work well. He says he’s already learned a couple of new functions from the app.

If you’re trying to learn Elisp, this may be a useful tool to get you started. Take a look at Hughes’ post to see if it might help you out. Regardless, it’s a neat hack and worth playing with just for the entertainment value.

Mike Zamansky has posted the latest Emacs video in his series. This time it’s about flycheck. As usual, the video is from the point of view of how Zamansky himself uses Emacs.

The demonstration is mostly about using flycheck with Python because that’s the language that Zamansky uses most of the time but he also shows an example of using it with C. He points to the flycheck home page and the list of supported languages, which includes Elisp, of course.

I often see queries on how to set up a Python environment in Emacs. Zamansky discusses that a bit too but doesn’t cover Elpy because it’s more powerful than he needs. He does talk about Pylint, Flake8, and Jedi, though. If you’re looking for a Python environment, check out this video. Those of you who haven’t tried flycheck yet should check it out too.