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Plugins

Micro supports creating plugins with a simple Lua system. Every plugin has a main script which is run at startup which should be placed in ~/.config/micro/plugins/pluginName/pluginName.lua.

There are a number of callback functions which you can create in your plugin to run code at times other than startup. The naming scheme is onAction(view). For example a function which is run every time the user saves the buffer would be:

function onSave(view)
    ...
    return false
end

The view variable is a reference to the view the action is being executed on. This is almost always the current view, which you can get with CurView() as well.

All available actions are listed in the keybindings section of the help.

For callbacks to mouse actions, you are also given the event info:

function onMousePress(view, event)
    local x, y = event:Position()

    return false
end

These functions should also return a boolean specifying whether the view should be relocated to the cursor or not after the action is complete.

Note that these callbacks occur after the action has been completed. If you want a callback before the action is executed, use preAction(). In this case the boolean returned specifies whether or not the action should be executed after the lua code completes.

Another useful callback to know about which is not an action is onViewOpen(view) which is called whenever a new view is opened and the new view is passed in. This is useful for setting local options based on the filetype, for example turning off tabstospaces only for Go files when they are opened.


There are a number of functions and variables that are available to you in order to access the inner workings of micro. Here is a list (the type signatures for functions are given using Go's type system):

  • OS: variable which gives the OS micro is currently running on (this is the same as Go's GOOS variable, so darwin, windows, linux, freebsd...)

  • configDir: contains the path to the micro configuration files

  • tabs: a list of all the tabs currently in use

  • curTab: the index of the current tabs in the tabs list

  • messenger: lets you send messages to the user or create prompts

  • NewBuffer(text, path string) *Buffer: creates a new buffer from a given reader with a given path

  • NewBufferFromFile(path string) *Buffer: creates a new buffer from a given path

  • GetLeadingWhitespace() bool: returns the leading whitespace of the given string

  • IsWordChar(str string) bool: returns whether or not the string is a 'word character'

  • RuneStr(r rune) string: returns a string containing the given rune

  • Loc(x, y int) Loc: returns a new Loc struct

  • WorkingDirectory() string: returns a rooted path name to the current working directory

  • JoinPaths(dir... string) string: combines multiple directories to a full path

  • DirectoryName(path string): returns all but the last element of path, typically the path's directory

  • GetOption(name string): returns the value of the requested option

  • AddOption(name string, value interface{}): sets the given option with the given value (interface{} means any type in Go)

  • SetOption(option, value string): sets the given option to the value. This will set the option globally, unless it is a local only option.

  • SetLocalOption(option, value string, view *View): sets the given option to the value locally in the given buffer

  • BindKey(key, action string): binds key to action

  • MakeCommand(name, function string, completions ...Completion): creates a command with name which will call function when executed. Use 0 for completions to get NoCompletion.

  • MakeCompletion(function string): creates a Completion to use with MakeCommand

  • CurView(): returns the current view

  • HandleCommand(cmd string): runs the given command

  • ExecCommand(name string, args []string) (string, error): exec a (shell) command with the given arguments. Returns the command's output and a possible error.

  • RunShellCommand(cmd string) (string, error): Run a shell command. This uses ExecCommand under the hood but also does some parsing for the arguments (i.e. quoted arguments). The function returns the command's output and a possible error.

  • RunBackgroundShell(cmd string): Run a shell command in the background.

  • RunInteractiveShell(cmd string, wait bool, getOutput bool) (string, error): Run a shell command by closing micro and running the command interactively. If wait is true, a prompt will be used after the process exits to prevent the terminal from immediately returning to micro, allowing the user to view the output of the process. If getOutput is true, the command's standard output will be returned. Note that if getOutput is true, some interactive commands may not behave normally because isatty will return false.

  • RunTermEmulator(cmd string, wait bool, getOutput bool, callback string) error: Same as RunInteractiveShell except the command is run within the current split in a terminal emulator. The callback input is a string callback to a lua function which will be called when the process exits. The output of the process will be provided as the first and only argument to the callback (it will be empty if getOutput is false). Note that this functionality is only supported on some operating systems (linux, darwin, dragonfly, openbsd, freebsd). Use the TermEmuSupported (see below) boolean to determine if the current system is supported.

  • TermEmuSupported: Boolean specifying if the terminal emulator is supported on the version of micro that is running.

  • ToCharPos(loc Loc, buf *Buffer) int: returns the character position of a given x, y location

  • Reload: (Re)load everything

  • ByteOffset(loc Loc, buf *Buffer) int: exactly like ToCharPos except it it counts bytes instead of runes

  • JobSpawn(cmdName string, cmdArgs []string, onStdout, onStderr, onExit string, userargs ...string): Starts running the given process in the background. onStdout onStderr and onExit are callbacks to lua functions which will be called when the given actions happen to the background process. userargs are the arguments which will get passed to the callback functions

  • JobStart(cmd string, onStdout, onStderr, onExit string, userargs ...string): Starts running the given shell command in the background. Note that the command execute is first parsed by a shell when using this command. It is executed with sh -c.

  • JobSend(cmd *exec.Cmd, data string): send a string into the stdin of the job process

  • JobStop(cmd *exec.Cmd): kill a job

This may seem like a small list of available functions but some of the objects returned by the functions have many methods. CurView() returns a view object which has all the actions which you can call. For example CurView():Save(false). You can see the full list of possible actions in the keybindings help topic. The boolean on all the actions indicates whether or not the lua callbacks should be run. I would recommend generally sticking to false when making a plugin to avoid recursive problems, for example if you call CurView():Save(true) in onSave(). Just use CurView():Save(false) so that it won't call onSave() again.

Using the view object, you can also access the buffer associated with that view by using CurView().Buf, which lets you access the FileType, Path, Name...

The possible methods which you can call using the messenger variable are:

  • messenger.Message(msg ...interface{})
  • messenger.Error(msg ...interface{})
  • messenger.YesNoPrompt(prompt string) (bool,bool)
  • messenger.Prompt(prompt, historyType string, completionType Completion) (string, bool)
  • messenger.AddLog(msg ...interface{})

Note

Go function signatures use . and lua uses : so

messenger.Message()

turns to

messenger:Message()

If you want a standard prompt, just use

messenger:Prompt(prompt, "", 0)

Debug or logging your plugin can be done with below lua example code.

messenger:AddLog("Message goes here ",pluginVariableToPrintHere)

In Micro to see your plugin logging output press CtrlE then type log, a logging window will open and any logging sent from your plugin will be displayed here.

Accessing the Go standard library

It is possible for your lua code to access many of the functions in the Go standard library.

Simply import the package you'd like and then you can use it. For example:

local ioutil = import("io/ioutil")
local fmt = import("fmt")

local data, err = ioutil.ReadFile("SomeFile.txt")

if err ~= nil then
    messenger:Error("Error reading file: SomeFile.txt")
else
    -- Data is returned as an array of bytes
    -- Using Sprintf will convert it to a string
    local str = fmt.Sprintf("%s", data)

    -- Do something with the file you just read!
    -- ...
end

Here are the packages from the Go standard library that you can access. Nearly all functions from these packages are supported. For an exact list of which functions are supported you can look through lua.go (which should be easy to understand).

fmt
io
io/ioutil
net
math
math/rand
os
runtime
path
filepath
strings
regexp
errors
time

For documentation for each of these functions, you can simply look through the Go standard library documentation.

Adding help files, syntax files, or colorschemes in your plugin

You can use the AddRuntimeFile(name, type, path string) function to add various kinds of files to your plugin. For example, if you'd like to add a help topic to your plugin called test, you would create a test.md file, and call the function:

AddRuntimeFile("test", "help", "test.md")

Use AddRuntimeFilesFromDirectory(name, type, dir, pattern) to add a number of files to the runtime. To read the content of a runtime file use ReadRuntimeFile(fileType, name string) or ListRuntimeFiles(fileType string) for all runtime files.

Autocomplete command arguments

See this example to learn how to use MakeCompletion and MakeCommand

local function StartsWith(String,Start)
    String = String:upper()
    Start = Start:upper() 
    return string.sub(String,1,string.len(Start))==Start
end

function complete(input)
    local allCompletions = {"Hello", "World", "Foo", "Bar"}
    local result = {}

    for i,v in pairs(allCompletions) do
        if StartsWith(v, input) then
            table.insert(result, v)
        end
    end
    return result
end

function foo(arg)
    messenger:Message(arg)
end

MakeCommand("foo", "example.foo", MakeCompletion("example.complete"))

Default plugins

For examples of plugins, see the default autoclose and linter plugins (stored in the normal micro core repo under runtime/plugins) as well as any plugins that are stored in the official channel here.

Plugin Manager

Micro also has a built in plugin manager which you can invoke with the > plugin ... command.

For the valid commands you can use, see the commands help topic.

The manager fetches plugins from the channels (which is simply a list of plugin metadata) which it knows about. By default, micro only knows about the official channel which is located at github.com/micro-editor/plugin-channel but you can add your own third-party channels using the pluginchannels option and you can directly link third-party plugins to allow installation through the plugin manager with the pluginrepos option.

If you'd like to publish a plugin you've made as an official plugin, you should upload your plugin online (to Github preferably) and add a repo.json file. This file will contain the metadata for your plugin. Here is an example:

[{
  "Name": "pluginname",
  "Description": "Here is a nice concise description of my plugin",
  "Tags": ["python", "linting"],
  "Versions": [
    {
      "Version": "1.0.0",
      "Url": "https://github.com/user/plugin/archive/v1.0.0.zip",
      "Require": {
        "micro": ">=1.0.3"
      }
    }
  ]
}]

Then open a pull request at github.com/micro-editor/plugin-channel adding a link to the raw repo.json that is in your plugin repository. To make updating the plugin work, the first line of your plugins lua code should contain the version of the plugin. (Like this: VERSION = "1.0.0") Please make sure to use semver for versioning.