Code Explainer | Lua

Memory Game Logic Overview

This document outlines the Lua code for a memory game, detailing its structure, functionality, and key components, including image highlighting, position tracking, and player interactions leveraging callback functions for visual updates.

Prompt

-- Importing necessary libraries
local memory = require("memory")

-- Storing selected positions
local selected_positions = {}

--- Highlights an image at a given position
-- @param position: The position of the image to be highlighted
local function highlight_image(position)
    -- Highlight logic (This is placeholder logic. Replace with actual game highlight code)
    print("Highlighting image at position: " .. position)
end

--- Clears all highlights/markers
local function clear_highlights()
    -- Logic to clear highlights (placeholder code)
    print("Clearing all highlights")
end

--- Updates the board whenever a new selection is made
-- @param position: The position of the newly selected image
-- @param color_change_callback: Callback to invoke when images should change color
local function update_board(position, color_change_callback)
    -- Validate position input
    assert(type(position) == 'number', "Position must be a number")

    -- If the position has already been selected, ignore it
    if selected_positions[position] then
        print("Position already selected: " .. position)
        return
    end

    -- Otherwise, store the selected position and image id
    selected_positions[position] = true

    -- Check if we have a match
    if memory.check_if_match_found(position) then
        -- Get the position of the previously selected matching image
        local previous_position = memory.get_previous_position(position)

        -- Highlight both the current and previous matching images
        highlight_image(position)
        highlight_image(previous_position)

        -- Invoke the callback to signal images should change color
        color_change_callback()
        
        -- Clear markers after highlighting
        clear_highlights()
    end
end

--- Callback function example for when the images change color
local function images_change_color()
    -- Placeholder code for changing color
    print("Images have changed color")
end

-- External Interface to interact with the game
local game_interface = {
    update_board = update_board
}

-- Example Usage
-- To update the board and process selections
game_interface.update_board(1, images_change_color)
game_interface.update_board(2, images_change_color)

Answer

Code Explanation

Importing Necessary Libraries

local memory = require("memory")

This line imports the memory module, which contains functions required for memory operations such as checking matches and retrieving previously selected positions.

Variable Declarations

local selected_positions = {}

This table is used to store positions that have been selected by the player.

Function Definitions

`highlight_image(position)`

local function highlight_image(position)
    print("Highlighting image at position: " .. position)
end

This function is responsible for highlighting an image at a given position. Currently, it only prints a message. In a complete game, this would involve actual logic to visually highlight the image.

`clear_highlights()`

local function clear_highlights()
    print("Clearing all highlights")
end

This function clears all current highlights or markers. As of now, it just prints a message but should contain logic to clear visual highlights in a complete implementation.

`update_board(position, color_change_callback)`

local function update_board(position, color_change_callback)
    assert(type(position) == 'number', "Position must be a number")

    if selected_positions[position] then
        print("Position already selected: " .. position)
        return
    end
    
    selected_positions[position] = true

    if memory.check_if_match_found(position) then
        local previous_position = memory.get_previous_position(position)
        highlight_image(position)
        highlight_image(previous_position)
        color_change_callback()
        clear_highlights()
    end
end

This function processes a new image selection by performing the following steps:

Input Validation: Ensures that the input position is a number.
Duplicate Check: Ignores positions that have already been selected.
Store Selection: Marks the position as selected.
Match Check: If a match is found, fetches the previous matching position, highlights both images, invokes the color_change_callback, and then clears all highlights.

`images_change_color()`

local function images_change_color()
    print("Images have changed color")
end

This placeholder function represents a callback that will be invoked when images should change color, indicated by the print statement.

External Interface

local game_interface = {
    update_board = update_board
}

The game_interface table exposes the update_board function to external code, allowing it to interact with the game.

Example Usage

game_interface.update_board(1, images_change_color)
game_interface.update_board(2, images_change_color)

These lines demonstrate how to use the update_board function to process selections at positions 1 and 2, invoking the images_change_color callback when necessary.

Summary

Libraries Import: Imports essential modules.
Variables: Stores selected positions.
Functionality:
- highlight_image: Placeholder for image highlighting logic.
- clear_highlights: Placeholder for clearing highlights.
- update_board: Main logic to update the game board, process selections, highlight matches, and invoke callbacks.
- images_change_color: Example callback function.
Interface & Example: Exposes update_board for external code and demonstrates usage.

This explanation should assist in understanding the code structure, functionality, and key concepts, enhancing overall comprehension. For further in-depth learning, exploring structured courses on the Enterprise DNA Platform can be beneficial.