Plugin development of hello xmake

xmake v2.0 has supported the plugin module and we can develop ourself plugin module conveniently.

We can run command xmake -h to look over some builtin plugins of xmake

    Plugins: 
        l, lua                                 Run the lua script.
        m, macro                               Run the given macro.
           doxygen                             Generate the doxygen document.
           hello                               Hello xmake!
           project                             Create the project file.

• lua: Run a given lua script.
• macro: Record and playback some xmake commands repeatly.
• doxygen：Generate doxygen document automatically.
• hello: The demo plugin and only print: 'hello xmake!'
• project：Generate project file for IDE, only generate makefile now and will generate vs, xcode project in the future

Next we write a simple plugin demo for printing 'hello xmake!'

    -- define a plugin task 
    task("hello")

        -- set the category for showing it in plugin category menu (optional)
        set_category("plugin")

        -- the main entry of the plugin
        on_run(function ()

            -- print 'hello xmake!'
            print("hello xmake!")
        end)

        -- set the menu options, but we put empty options now.
        set_menu({
                        -- usage
                        usage = "xmake hello [options]"

                        -- description
                    ,   description = "Hello xmake!"

                        -- options
                    ,   options = {}
                    }) 

The file tree of this plugin:

    hello
     - xmake.lua

Now one of the most simple plugin finished, how was it to be xmake detected it, there are three ways:

1. Put this plugin directory into xmake/plugins the source codes as the builtin plugin.
2. Put this plugin directory into ~/.xmake/plugins as the global user plugin.
3. Put this plugin directory to anywhere and call add_plugindirs("./hello") in xmake.lua as the local project plugin.

Next we run this plugin

    $xmake hello

The results is

    hello xmake!

Finally, we can also run this plugin in the custom scripts of xmake.lua

    target("demo")

        -- run this plugin after building target
        after_build(function (target)

            -- import task module
            import("core.project.task")

            -- run the plugin task
            task.run("hello")
        end)