Unreal Software - Thread: Threaded hooks in cs2d

Threaded hooks in cs2d

Livia
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Offline

24.01.17 11:57:27 pm

Hello everyone,

I love to create abstract stuff with lua and came up with some weird hook-thread combination. It uses coroutines, metatables and some hidden magic. It allows you to use sleep almost anywhere in your code. I can't think of any practical applications yet but it's rather cool anyway.

This is a continuation to my last attempt in lua threading.

Here we go:

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-- create a threaded say hook
threadhook('say', function(id, message)
    if message == 'suicide' then
        yield(1) -- don't display message in chat
    
        msg2(id, 'You are about to suicide in 3 seconds!')
        sleep(1000)

        msg2(id, '2..')
        sleep(1000)

        msg2(id, '1..')
        sleep(1000)

        parse('killplayer ' .. id)
    end 
end)

A threadhook allows you to yield the return value beforehand (line 4). It can also pause execution with sleep (lines 7, 10, 13).

Why would you want to wrap all the hooks inside threads? Because cs2d lua is all about running code which react to different hooks. If you cover all the hooks inside threadhooks, you can freely use sleep and yield anywhere in your code!

In this example we're using sleep inside another function, and it works fine

You could even use yield in another function and the first one called will be returned to the hook. This allows you to parse chat commands anywhere and not having to worry about return values and complex program flow! Once you cover all your hooks inside threadhooks things get very interesting... eg. you could create a menu function that waits for the user entry and returns the button pressed as a value, no need to manually handle menu hooks.

Okay if you're not sold on the threadhooks, there's also a manual way to create threads.

I would love to hear your feedback!

thread.lua

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-- temporary table for storing sleeping coroutines
local thread_table = {}

-- returns unique identifier for a coroutine
local thread_get_id = function(co)
    return tostring(co):sub(11)
end

-- queues current coroutine for later execution
sleep = function(time)
    local co = coroutine.running()

    if co then
        local id = thread_get_id(co)
        thread_table[id] = co

        timer(time, 'thread_timer', id)

        coroutine.yield()
    end
end

-- yields a value and sleeps for 0ms
yield = function(value)
    local co = coroutine.running()

    if co then
        local id = thread_get_id(co)
        thread_table[id] = co

        timer(0, 'thread_timer', id)

        coroutine.yield(value)
    end
end

-- resumes the coroutine by id
thread_timer = function(id)
    local co = thread_table[id]
    thread_table[id] = nil

    coroutine.resume(co)
end

-- creates a coroutine with custom environment
thread = function(func, ...)
    local co = coroutine.create(func)
    local ok, res = coroutine.resume(co, unpack({...}))

    -- handle return value from the coroutine
    if ok then
        -- return the first yielded value
        return res
    else
        -- print lua errors in coroutines manually
        print('THREAD ERROR: ' .. res)
    end
end

local hook_counter = 1
-- a table for creating and storing threaded hooks
threadhook = setmetatable({}, {
    __call = function(_, name, func)
        local id = name .. hook_counter
        hook_counter = hook_counter + 1

        addhook(name, 'threadhook.' .. id)

        threadhook[id] = function(...)
            return thread(func, unpack({...}))
        end
    end
})

Re: Threaded hooks in cs2d

VADemon
User Off

Offline

25.01.17 02:28:29 am

I'd not use it for menus, because we have 2 forks of UniMenu already (I can't comprehend how people are still going after the malady of manually scripting menus...).

However it's great for some situations that require this kind of pause/execution:

delayed and time quant based execution

wait-for-reply commands (such as confirmation dialogues)

anything else that requires sequential action

But I'm not sure about the last point. Would I dynamically create a new thread/function for each advanced command or is there another way?

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Threaded hooks in cs2d