spacemacs/doc/CONVENTIONS.org

* Spacemacs conventions

** Table of Contents                                                 :TOC@4:
 - [[#spacemacs-conventions][Spacemacs conventions]]
     - [[#code-guidelines][Code guidelines]]
         - [[#spacemacs-core-and-layer][Spacemacs core and layer]]
         - [[#all-layers][All layers]]
     - [[#key-bindings-conventions][Key bindings conventions]]
         - [[#reserved-prefix][Reserved prefix]]
             - [[#user-prefix][User prefix]]
             - [[#major-mode-prefix][Major mode prefix]]
             - [[#micro-state][Micro-state]]
         - [[#evilify-buffers][Evilify buffers]]
         - [[#navigation][Navigation]]
             - [[#n-and-n][n and N]]
             - [[#code-navigation][Code Navigation]]
             - [[#insert-state-buffers][=insert state= buffers]]
         - [[#evaluation][Evaluation]]
         - [[#repls][REPLs]]
             - [[#send-code][Send code]]
             - [[#in-terminal][In terminal]]
         - [[#building-and-compilation][Building and Compilation]]
         - [[#debugging][Debugging]]
         - [[#plain-text-markup-languages][Plain Text Markup Languages]]
             - [[#headers][Headers]]
             - [[#insertion-of-common-elements][Insertion of common elements]]
             - [[#text-manipulation][Text manipulation]]
             - [[#movement-in-normal-mode][Movement in normal mode]]
             - [[#promotion-demotion-and-element-movement][Promotion, Demotion and element movement]]
             - [[#table-editing][Table editing]]
         - [[#tests][Tests]]
             - [[#all-languages][All languages]]
             - [[#language-specific][Language specific]]
         - [[#refactoring][Refactoring]]
         - [[#help-or-documentation][Help or Documentation]]
     - [[#writing-documentation][Writing documentation]]
         - [[#spacing-in-documentation][Spacing in documentation]]

** Code guidelines
*** Spacemacs core and layer
Function names follow these conventions:
  - =spacemacs/xxx= is an interactive function called =xxx=
  - =spacemacs//xxx= is a private function called =xxx= (implementation details)
  - =spacemacs|xxx= is a /macro/ called =xxx=

Variables follow these conventions:
  - =spacemacs-xxx= is a variable
  - =spacemacs--xxx= is a private variable (implementation details)

*** All layers
A package is initialized in a function with name =<layer>/init-xxx= where:
  - =<layer>= is the layer name
  - =xxx= is the package name

** Key bindings conventions

*** Reserved prefix
**** User prefix
~SPC o~ must not be used by any layer. It is reserved for the user.

**** Major mode prefix
~SPC m~ is reserved for the current major mode. Three keys bindings are not an
issue (ie. ~SPC m h d~) since ~SPC m~ can be accessed via ~,~.

**** Micro-state
Whenever possible a micro-state should be enabled with ~M-SPC~ and ~s-M-SPC~. We
need the latter bindings on OS X since ~M-SPC~ is used by the OS for spotlight.

For instance micro-states dedicated to special buffers like =helm= or =ido=
buffers are good candidates to be put on ~M-SPC~ and ~s-M-SPC~.

It is recommended to add ~q~ to leave the micro-state.

*** Evilify buffers
=Spacemacs= offers convenient functions to /evilify/ a buffer.
/Evilifying/ a buffer is to set the =evilified state= as the default
state for the major mode of the buffer.

The =evilified state= is derived from the =emacs state= and modify the
map to: - add ~hjkl~ navigation - add incremental search with ~/~, ~n~
and ~N~ - add =visual state= and =visual line state= - add yank (copy)
with ~y~ - activate evil-leader key

Setting the =evilified state= to a mode is done by calling the macro
=evilify= which takes optional parameters to fix the key bindings
shadowed by the above modifications.

To fix the shadowed bindings we capitalize them, for instance: shadowed
~h~ is transposed to ~H~, if ~H~ is taken then it is transposed to ~C-h~
and so on...

Example of /evilified/ buffers are =magit status=, =paradox buffer=.

*** Navigation
**** n and N
To be consistent with the Vim way, ~n~ and ~N~ are favored over Emacs ~n~ and
~p~.

Ideally a micro-state should be provided to smooth the navigation
experience. A micro-state allows to repeat key bindings without entering
each time the prefix commands. More info on micro-states in the
[[DOCUMENTATION.org#micro-states][documentation]].

**** Code Navigation
The prefix for going to something is ~SPC m g~.

| Key     | Description                                |
|---------+--------------------------------------------|
| ~m g a~ | go to alternate file (i.e. =.h <--> .cpp=) |
| ~m g g~ | go to things under point                   |
| ~m g G~ | go to things under point in other window   |
| ~m g t~ | go to corresponding test file if any       |

**** =insert state= buffers
Navigation in buffers like =Helm= and =ido= which are in =insert state=
should be performed with ~C-j~ and ~C-k~ bindings for vertical movements.

| Key   | Description |
|-------+-------------|
| ~C-j~ | go down     |
| ~C-k~ | go up       |

*** Evaluation
Live evaluation of code is under the prefix ~SPC m e~.

| Key     | Description                                       |
|---------+---------------------------------------------------|
| ~m e $~ | put the point at the end of the line and evaluate |
| ~m e b~ | evaluate buffer                                   |
| ~m e e~ | evaluate last expression                          |
| ~m e f~ | evaluate function                                 |
| ~m e l~ | evaluate line                                     |
| ~m e r~ | evaluate region                                   |

*** REPLs
**** Send code
A lot of languages can interact with a REPL. To help keeping a
consistent behavior between those languages the following conventions
should be followed:
  - ~SPC m s~ is the prefix for sending code. This allows fast interaction with
    the REPL whenever it is possible
  - lower case key bindings keep the focus on the current buffer
  - upper case key bindings move the focus to the REPL buffer

| Key     | Description                                                  |
|---------+--------------------------------------------------------------|
| ~m s b~ | send buffer                                                  |
| ~m s B~ | send buffer and switch to REPL                               |
| ~m s d~ | first key to send buffer and switch to REPL to debug (step)  |
| ~m s D~ | second key to send buffer and switch to REPL to debug (step) |
| ~m s f~ | send function                                                |
| ~m s F~ | send function and switch to REPL                             |
| ~m s i~ | start/switch to REPL inferior process                        |
| ~m s l~ | send line                                                    |
| ~m s L~ | send line and switch to REPL                                 |
| ~m s r~ | send region                                                  |
| ~m s R~ | send region and switch to REPL                               |

Note: we don't distinguish between the file and the buffer.

**** In terminal
History navigation in shells or REPLs buffers should be bound as well to
~C-j~ and ~C-k~.

    | Key   | Description                |
    |-------+----------------------------|
    | ~C-j~ | next item in history       |
    | ~C-k~ | previous item in  history  |
    | ~C-l~ | clear screen               |
    | ~C-r~ | search backward in history |

*** Building and Compilation
The base prefix for major mode specific compilation is ~SPC m c~.

    | Key Binding | Description       |
    |-------------+-------------------|
    | ~m c b~     | compile buffer    |
    | ~m c c~     | compile           |
    | ~m c r~     | clean and compile |

Note: we don't distinguish between the file and the buffer. We can
implement an auto-save of the buffer before compiling the buffer.

*** Debugging
The base prefix for debugging commands is ~SPC d~.

| Key Binding | Description             |
|-------------+-------------------------|
| ~m d a~     | abandon current process |
| ~m d b~     | toggle a breakpoint     |
| ~m d B~     | clear all breakpoints   |
| ~m d c~     | continue                |
| ~m d d~     | start debug session     |
| ~m d i~     | inspect value at point  |
| ~m d l~     | local variables         |
| ~m d n~     | next                    |
| ~m d r~     | run                     |
| ~m d s~     | step                    |

Notes:
  - Ideally a micro-state for breakpoint navigation should be provided.
  - If there is no toggle breakpoint function, then it should be implemented at
    the spacemacs level and ideally the function should be proposed as a patch
    upstream (major mode repository).

*** Plain Text Markup Languages
For layers supporting markup languages please follow the following
keybindings whenever applicable.

**** Headers
All header functionality should be grouped under ~SPC m h~

| Key Binding | Description                                      |
|-------------+--------------------------------------------------|
| ~m h i~     | Insert a header                                  |
| ~m h I~     | Insert a header alternative method (if existing) |
| ~m h 1..10~ | Insert a header of level 1..10 (if possible)     |

**** Insertion of common elements
Insertion of common elements like links or footnotes should be grouped
under ~SPC m i~

| Key Binding | Description      |
|-------------+------------------|
| ~m i f~     | Insert footnote  |
| ~m i i~     | Insert image     |
| ~m i l~     | Insert link      |
| ~m i u~     | Insert url       |
| ~m i w~     | Insert wiki-link |

**** Text manipulation
Manipulation of text regions should be grouped under ~SPC m r~

| Key Binding | Description                   |
|-------------+-------------------------------|
| ~m x b~     | Make region bold              |
| ~m x c~     | Make region code              |
| ~m x i~     | Make region italic            |
| ~m x q~     | Quote a region                |
| ~m x r~     | Remove formatting from region |
| ~m x s~     | Make region strike-through    |
| ~m x u~     | Make region underlined        |
| ~m x v~     | Make region verbose           |

**** Movement in normal mode
In normal mode Vim style movement should be enabled with these keybindings:

| Key Binding | Description                            |
|-------------+----------------------------------------|
| ~g h~       | Move up one level in headings          |
| ~g j~       | Move to next heading on same level     |
| ~g k~       | Move to previous heading on same level |
| ~g l~       | Move down one level in headings        |

**** Promotion, Demotion and element movement
Promotion, demotion and movement of headings or list elements (whatever is
possible) should be enabled with the following keys in any mode

| Key Binding | Description                  |
|-------------+------------------------------|
| ~M-h~       | Promote heading by one level |
| ~M-j~       | Move element down            |
| ~M-k~       | Move element up              |
| ~M-l~       | Demote heading by one level  |

**** Table editing
If table specific commands are available the they are grouped under the
~SPC m t~ group.

*** Tests
A lot of languages have their own test frameworks. These frameworks
share common actions that we can unite under the same key bindings: -
~SPC m t~ is the prefix for test execution. - ~SPC m T~ is the
prefix for test execution in debug mode (if supported).

**** All languages
| Key     | Description                                         |
|---------+-----------------------------------------------------|
| ~m t a~ | execute all the tests of the current project        |
| ~m t b~ | execute all the tests of the current buffer         |
| ~m t t~ | execute the current test (thing at point, function) |

Note: we don't distinguish between the file and the buffer. We can
implement an auto-save of the buffer before executing the tests of
buffer.

**** Language specific
| Key     | Description                             |
|---------+-----------------------------------------|
| ~m t m~ | execute the tests of the current module |
| ~m t s~ | execute the tests of the current suite  |

Note that there are overlaps, depending on the language we will choose
one or more bindings for the same thing

*** Refactoring
Refactoring prefix is ~SPC m r~.

*** Help or Documentation
The base prefix for help commands is ~SPC h~. Documentation is considered
as an help command.

| Key     | Description                        |
|---------+------------------------------------|
| ~m h h~ | documentation of thing under point |
| ~m h r~ | documentation of selected region   |

** Writing documentation
Spacemacs provides an example layer =README.org= file in
=~/.emacs.d/core/templates/layer-README.template=.

*** Spacing in documentation
Spacemacs tries to keep the documentation consistent between all layers by
providing some rules for spacing:
  - After each header, you should not add an empty line
    - *Exception*: If the first item under the header is a table, add an empty
      line after it
  - At the end of each header node, there should be an empty line
  - Note: Many layer =READMEs= do not follow this convention yet. Please fix
    them if you can.