Two Syntax Styles of xmake

Recently, xmake’s description syntax has been enhanced to support two different grammar styles at the same time.

The set-add style
The key-val style

The `set-add` style

This is xmake’s classic style, for example:

target("test")
    set_kind("static")
    add_defines("DEBUG")
    add_files("src/*.c", "test/*.cpp")

Advantages: more flexible control, you can control a variety of highly complex configuration requirements.
Disadvantages: scope control is not obvious, need to manually standardized indentation

The `key-val` style

This is added style recently, for example:

target
{
    name = "test",
    defines = "DEBUG",
    files = {"src/*.c", "test/*.cpp"}
}

Advantages: more readable
Disadvantages: conditional compilation is not very flexible

These two styles, xmake are currently compatible with the support, but our recommendations are:

For simple projects, do not need too complicated conditional compilation, you can use the key-val way, more streamlined, good readability
For complex engineering, the need for greater control, and flexibility, it is recommended to use set-add way
Try not to mix and write the two styles, although it is supported, but this description of the entire project will feel confused, so try to unify the style as their description of the specification

In addition, not only for target, like option, task, template are supported in two ways to write, for example:

-- set-add style
option("demo")
    set_default(true)
    set_showmenu(true)
    set_category("option")
    set_description("Enable or disable the demo module", "    =y|n")

-- key-val style
option
{
    name = "demo",
    default = true,
    showmenu = true,
    category = "option",
    desciption = {"Enable or disable the demo module", "    =y|n"}
}

The custom tasks or plugins can be written like this:

-- set-add style
task("hello")

    -- on run
    on_run(function ()

        -- trace
        print("hello xmake!")

    end)

    -- set menu
    set_menu({
                    -- usage
                    usage = "xmake hello [options]"

                    -- description
                ,   description = "Hello xmake!"

                    -- options
                ,   options = {}
                }) 

-- key-val style
task
{
    name = "hello",
    run = (function ()

        -- trace
        print("hello xmake!")

    end),
    menu = {
                -- usage
                usage = "xmake hello [options]"

                -- description
            ,   description = "Hello xmake!"

                -- options
            ,   options = {}
            }
}