Hotswap

Hotswap allows you to update class definitions at runtime, automatically updating existing instances with new members.

Enabling Hotswap

Enable hotswap before loading any classes:

simploo.config["classHotswap"] = true
dofile("simploo.lua")

Or initialize it manually:

dofile("simploo.lua")
simploo.hotswap:init()

How It Works

When you redefine a class, existing instances are updated:

• New members are added to existing instances
• Removed members are deleted from existing instances
• Existing member values are preserved

-- Initial definition
class "Player" {
    name = "";
    health = 100;
}

local player = Player.new()
player.name = "Alice"
player.health = 75

-- Redefine the class
class "Player" {
    name = "";
    health = 100;
    mana = 50;  -- New member added
    -- 'destroy' was removed
}

-- Existing instance is updated
print(player.name)    -- Alice (preserved)
print(player.health)  -- 75 (preserved)
print(player.mana)    -- 50 (new member with default value)

What Gets Updated

Updated	Not Updated
New members added	Existing values
Removed members deleted	Modified instance data
Method implementations	Default values for existing members
Default values for new members

Use Case: Development

Hotswap is useful during development when you want to iterate quickly:

-- Enable hotswap for development
simploo.config["classHotswap"] = true

-- Your game loop
while running do
    -- Check if source files changed
    if filesChanged() then
        -- Reload class definitions
        dofile("classes/player.lua")
        dofile("classes/enemy.lua")
        -- Existing instances automatically get new members!
    end

    updateGame()
    renderGame()
end

Limitations

1. Values are not updated: If you change a default value, existing instances keep their old values
2. Memory overhead: Hotswap tracks all instances, using more memory
3. Performance: Slight overhead on instance creation

class "Example" {
    value = 10;
}

local e = Example.new()
print(e.value)  -- 10

-- Redefine with new default
class "Example" {
    value = 999;  -- Changed default
}

print(e.value)  -- Still 10, not 999

Memory Considerations

Hotswap uses weak references, so instances can still be garbage collected:

simploo.config["classHotswap"] = true

class "Temp" {}

local t = Temp.new()
-- t is tracked for hotswap

t = nil
collectgarbage()
-- t is garbage collected despite hotswap tracking

Disabling Hotswap

For production, disable hotswap to improve performance:

simploo.config["classHotswap"] = false
simploo.config["production"] = true

Complete Example

simploo.config["classHotswap"] = true
dofile("simploo.lua")

-- Initial class
class "Character" {
    name = "";
    health = 100;

    takeDamage = function(self, amount)
        self.health = self.health - amount
    end;
}

-- Create some instances
local hero = Character.new()
hero.name = "Hero"
hero.health = 50

local villain = Character.new()
villain.name = "Villain"
villain.health = 80

-- Later, redefine the class with a new feature
class "Character" {
    name = "";
    health = 100;
    shield = 0;  -- New!

    takeDamage = function(self, amount)
        local absorbed = math.min(self.shield, amount)
        self.shield = self.shield - absorbed
        self.health = self.health - (amount - absorbed)
    end;
}

-- Existing instances now have shield
print(hero.shield)     -- 0 (new member with default)
print(villain.shield)  -- 0 (new member with default)

-- Existing values preserved
print(hero.name)       -- Hero
print(hero.health)     -- 50
print(villain.name)    -- Villain
print(villain.health)  -- 80