git clone 'git://github.com/davidshepherd7/electric-operator.git'
An emacs minor-mode to automatically add spacing around operators.
For example typing
a = 10 * 5 + 2
I'm aiming to have electric-operator-mode “correctly” handle almost every operator for major modes built in to Emacs (and a few that aren't). If you find a case where it doesn't space something as expected then consider it a bug, and please report it :).
The simplest way to install electric-operator-mode is by using package.el
to get it from MELPA unstable.
Alternatively you can install the dependencies listed in
electric-operator.el and add
electric-operator.el to your load path.
Either way you also need to make sure electric-operator is loaded with
(require 'electric-operator) (or you could use
use-package to load packages
and keep your customisations organised).
To temporarily enable electric-operator-mode simply call
electric-operator-mode. To permenantly enable it for a major mode simply
add it to the relevant mode hook. For example for python-mode add the
following to your config:
(add-hook 'python-mode-hook #'electric-operator-mode)
electric-operator-mode is not a global minor mode, and so must
be enabled separately for each major mode.
The spacing around operators is controlled by “rules”. The simplest rule is
a pair containing the (unspaced) operator and the correctly spaced operator
as strings. For example
(cons "=" " = ") is the default rule for
Alternatively the second element of the pair can be a function which
returns the correctly spaced operator.
Each major mode has its own list of rules for the spacing of operators. The
rule list for a major mode is looked up in the hash table
electric-operator-mode-rules-table. Rule lists can be modified using the
electric-operator-add-rules-for-mode, which will automatically
replace any existing rules for the same operator. To disable a rule set the
action part of the rule (the second element) to nil.
As an example: to automatically add spacing around
=> in python
mode you would use
(electric-operator-add-rules-for-mode 'python-mode (cons "->" " -> ") (cons "=>" " => "))
To use the default rules for a new programming mode use
apply to add all
(apply #'electric-operator-add-rules-for-mode 'my-new-mode electric-operator-prog-mode-rules)
The default rules for text modes can be added in the same way from the list
A number of basic operator rules are defined for any major mode, so if your language is “normal” (i.e C-like) then a good amount of functionality should just work.
Python: I've used
electric-operator a lot for python. Support is
extremely good. Specifically we handle edge cases in
: in dictionaries, kwarg assignment, and slices.
ess-mode: At least one person is using
ess-mode for R. R's syntax is fairly standard and straightforward, so
everything should work well. Using
ess-mode for languages other than
R is not currently supported.
C and C++: these are much more tricky to get right. Most things should be working ok but there are still some issues with pointer-to-class/struct types (#11) and templates (#8). I'm actively working on this.
Java: I've added tweaks based on memory and a syntax guide. Since the syntax is largely simlar a simplification of C++ it should work well, but I haven't tried it out yet. Generics aren't handled properly (#8).
Ruby and Perl: some tweaks for these modes were inherited from
electric-spacing, but I haven't tried them personally. Pull requests
Haskell: I've added a number of tweaks based on memory and skimming a syntax guide, but I haven't had a chance to try it out yet. There's probabaly some work to do.
Lisps: I don't think
electric-operator has much to offer for lisps, so
it doesn't do anything at the moment. If you can think of any spacing
rules that would be nice then please submit an issue/pull-request.
Text modes: Again, I'm not sure that we can do much in text modes. At the moment
spacing is added after
. (behaviour inherited from
If you use
electric-operator for a major mode not on this list please
open an issue to let me know how it went.
I'm using Cask to manage dependencies,
so to run the tests you'll need to install cask then run
cask install to
install dependencies. Then the tests can be run with
Bug reports are also welcome!
Electric-operator is based on a heavily refactored version of electric-spacing by William Xu with contributions from Nikolaj Schumacher. Electric-spacing is itself based on smart-operator, also by William Xu.
Electric-operator uses simpler and more flexible rules to define how
operators should be treated, and also adds a full suite of tests. However
it has some additional dependencies (in particular the excellent
names packages) which were decided
to be too heavy to add to electric-spacing.