custom-modders.md

Custom Modders

MVS gives you the ability to create custom module systems, called Modders. Modder is the struct name for the internal code which controls how modules and vendoring is handled. You can configure as many of these as you like, by providing global or local .mvsconfig.cue files.

See the following two files for the configuration options and defaults built into the tool:

• Definition: lib/modder/modder.go
• Defaults: lib/langs.go and .mvsconfig.cue

You create your own modders by createing .mvsconfig.cue files. MVS will look for these in two places before any commands are run.

• A global $HOME/.mvs/config.cue
• A local ./.mvsconfig.cue

MVS config file format

// These two need to be the same
cue: {
	Name: "cue"
	// non-semver of the language
	Version: "#.#.#"

	// Common defaults, can be anything
	ModFile:  "<lang>.mods"
	SumFile:  "<lang>.sums"
	ModsDir:  "<lang>.mod/pkg"
	Checksum: "<lang>.mod/checksum.txt"

	// Controls for modders that want to shell out
	// to common tools for certain commands
	NoLoad: false
	CommandInit: [[string]]
	CommandGraph: [[string]]
	CommandTidy: [[string]]
	CommandVendor: [[string]]
	CommandVerify: [[string]]
	CommandStatus: [[string]]

	// Runs on init for this language
	// filename/content key/pair values
	// uses the golang text/template library
	// inputs will be
	//   .Language
	//   .Module
	//   .Modder
	InitTemplates: {
		"<lang>.mod/module.<lang>": """
          module "{{ .Module }}"
          """
	}
	// Series of commands to be executed pre/post init
	InitPreCommands: [[string]]
	InitPostCommands: [[string]]

	// Same as the InitTemplates, but run during vendor command
	VendorTemplates: {
		"<lang>.mod/module.<lang>": """
          module "{{ .Module }}"
          """
	}

	VendorIncludeGlobs: [
		".mvsconfig.cue",
		"<lang>.mods",
		"<lang>.sums",
		"<lang>.mod/module.<lang>",
		"<lang>.mod/modules.txt",
		"**/*.<lang>",
	]
	VendorExcludeGlobs: ["<lang>.mod/pkg"]

	// Series of commands to be executed pre/post vendoring
	VendorPreCommands: [[string]]
	VendorPostCommands: [[string]]

	// Use MVS to only manage the languages normal dependency file
	ManageFileOnly: false

	// Whether local replaces should use a symlink instead of copying files
	SymlinkLocalReplaces: false

	// Controls the code introspection for dependency determiniation
	IntrospectIncludeGlobs: ["**/*.<lang>"]
	IntrospectExcludeGlobs: ["<lang>.mod/pkg"]
	IntrospectExtractRegex: ["you will have to figure out a series of 'any match passes' regexps to pull out dependencies"]

	// This field determines the prefix to place in front of
	// imports which have a single token or leverage package managers
	// This is currently futurology for building MVS for Python and JavaScript
	PackageManagerDefaultPrefix: "npm.js"
}