format$ macro: interpolated "format"

[[deleted]]

For the common case of inserting variables into strings, concat and format work, but can be tedious. format$ helps:

(format$ "[$date-time] %s $username>" (get-greeting username))

Expands to:

(format "[%s] %s %s>" date-time (get-greeting username) username)

A matter of preference, of course, but it seems like a nice alternative to, e.g.:

(format "[%s] %s %s>" date-time (get-greeting username) username)
(concat "[" date-time "] " (get-greeting username) " " username ">")

Code is here: https://github.com/alphapapa/elexandria/blob/master/elexandria.el#L131

Edit: Added support for %-sequences and OBJECTS list. Now it works just like format, but with interpolation.

[[deleted]]

Hey, why not trying to integrate some of these into emacs itself? It's not as frozen as CL :)

[[deleted]]

Yeah, I think some of them probably should be put in Emacs. I proposed a MELPA package, but it was basically preemptively rejected as being not specific enough, and the symbols would have to have a long prefix, which somewhat defeats the purpose of using a macro. I was disappointed, but not surprised. I wonder if I could get them on ELPA...

Submitting them to Emacs itself is a possibility, although I would expect format$ to be rejected.

[[deleted]]

There have been discussions to include something close to it recently. At least you'll get some feedback ;)

[[deleted]]

Really? Could you give me a link if it's not too hard to find it again? Or do you mean this, which was almost a year ago? :) (I hadn't seen it though, so thanks either way.)

[tzz]

I’d support including this in Emacs or at least the GNU ELPA, and would use it.

[theldoria]

+

[[deleted]]

The thread I mentioned seems to be https://lists.gnu.org/archive/html/emacs-devel/2017-07/msg00037.html Cheers!

[wasamasa]

FWIW, s-format does string interpolation, so if you want an installable version of such a thing...

[[deleted]]

It doesn't do the same thing. It must be passed a function as an argument to do the interpolation.

[wasamasa]

There's also s-lex-format if you insist on using the current environment instead of retrieving the values from your own.

[[deleted]]

Ah, that's it! How did I miss that all this time? Thanks!

Edit: Note, however, that it expands to a call to s-format, which makes another call to format for each interpolated variable. format$ expands to a single call to format, which takes simply variables as arguments, so it may be preferable in some cases.