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base class

I would need your help, please.

I don't know how to create a base class for my enemies.

For example I have one enemy class:
Enemy01 = Core.class(Sprite)
function Enemy01:init(xname, xposx, xposy)
	-- settings
	self.name = xname
	self.x = xposx
	self.y = xposy
	self.vx = 0
	self.vy = 0
	self.flip = 1
	self.isonfloor = false
	self.isattacking = false
	self.lives = 3
	self.accel = 500
	self.friction = 150
	self.maxspeed = 150
	self.jumpspeed = GRAVITY / 2
function Enemy01:createAnim(xanimname, xstart, xfinish, xanimslist)
	self.anims[xanimname] = {}
	for i = xstart, xfinish do
		self.anims[xanimname][#self.anims[xanimname] + 1] = xanimslist[i]

I have different enemies which would have different parameters value.
How can I make a base class which my enemies would inherit (variables and functions).

I have searched on the forum but I don't know how to handle this.

Thank you in advance for your time.
my growING GIDEROS github repositories: https://github.com/mokalux?tab=repositories


  • Apollo14Apollo14 Member
    edited August 2019 Accepted Answer
    EnemyAdvanced = Core.class(Enemy01)
    function EnemyAdvanced:init()

    Likes: hgy29, MoKaLux

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  • hgy29hgy29 Maintainer
    Accepted Answer
    Note that when using Core.class() to create a sub-class, the arguments sent to your new/init function will be used to call the superclass init too, which can have undesired effects. To handle this, I use my own Core.class call:
    Core.classArgs=function (p,a)
    	local c=Core.class(p)
    	c.__new = function(...)
    		local b = getmetatable(c)
    		local s1 = b.__new(a(...))
    		setmetatable(s1, c)
    		local init = rawget(c, "init")
    		if type(init) == "function" then
    			init(s1, ...)
    		return s1
    	return c
    It takes a second argument, which is a function that will return the arguments intended for the superclass based on the new class constructor arguments. Example:
    -- Define a new class to make a 50x50 pixel. Argument is the plain color	
    Pixel50=Core.classArgs(Pixel,function(color) return color,1,50,50 end)
    --Use it
    stage:addChild(Pixel50.new(0xFF0000)) -- Create a 50x50 red pixel
    I was thinking about enhancing gideros Core.class to do the same (if second arg is present), what do you think ?
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  • thank you guys for the answers.

    @Apollo14 I knew this bit Enemy02 = Core.class(Enemy) but then what do I put in the init()? only the values that are going to change? For example:
    Enemy02 = Core.class(Enemy)
    function Enemy02:init()
       self.vx = 30
       self:createAnim("walk", 1, 6, myanims_list)
    Ok, I should experiment more. Right now I do it the "easy" way but I feel like my code isn't nice.

    @hgy29 I have read on the forum about Core.class and how it is implemented by @atilim . That is a little bit too advanced for me :/ so I cannot tell what should be done.
    my growING GIDEROS github repositories: https://github.com/mokalux?tab=repositories
  • antixantix Member
    Accepted Answer
    With my games I haven't had to create subclasses, I just have a class for enemy which gets passed options that are overwritten on init() to make it different to other enemies. In fact all of my GUI objects use the same method.
    Enemy = Core.class(Bitmap)
    function Enemy:init(texture, options)
      -- default options
      self.position         = {x = 0, y = 0},
      self.velocity         = {x = 0, y = 0},
      self.alive            = true,
      self.type            = 'MUTANT',
      self.canBeClicked     = true
      -- copy any supplied options
    	if options then
    		for key, value in pairs(options) do
    			self[key]= value
      -- etc, etc
    Not the greatest code in the world maybe, but it works.

    Likes: MoKaLux

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  • @antix excellent, I am ending up doing something similar, maybe not the best way but it's easier for me! Thank you for sharing.

    Likes: antix

    my growING GIDEROS github repositories: https://github.com/mokalux?tab=repositories
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