crush/README.md

crush

crush - The uncomplicated LÖVE external module system.

crush is a minimalistic dependency-less package system for the LÖVE engine. It provides a structured approach to retrieve external libraries for your game project.

Why?

Lua knows some excellent dependency management system, like LuaRocks. Though, they are inconvenient for a game project, where:

• External libraries should be packed along with the game for distribution.
• Libraries are often small, and their code should be readily hackable by developers (library versions are not tremendously important).
• Depending on a complex package manager is undesireable.

LÖVE games have limited ways to manage external libraries:

1. Manually, directly copying external libraries in the game source tree.

   • Pulling latest changes in the library requires more copy-pasting.
   • Harder to use libraries if they depend on other libraries themselves.

2. Using a package manager during development, and carefully pack external libraries with the game manually upon distribution.

   • Introduce additional step to distribution phase.
   • Many existing LÖVE libraries have no package manager support.

crush provides an alternative approach, offering the following features:

• Fetch external libraries directly from their source code repository, ensuring the ability to pull, or even push, the latest changes from your project.
• Automatically pack external libraries inside the project source tree, inside a well-known lib folder.
• Resolves dependencies recursively, making possible for libraries that depend on other libraries, saving the developer all the manual dependency tracking.
• Works automatically with most existing LÖVE libraries, since it directly uses git to clone their sources.
• Does not require any complex package manager or native code, just a single Lua source file.
• Does not require any centralized package repository to publish or fetch libraries.

How to use it?

To use crush follow these steps:

1. Copy the latest crush.lua into your project's root folder.
2. Create a .lovedeps file in the same directory, here you will list every dependency (more in the next section).
3. Once you have crush.lua and .lovedeps in place, you can populate or refresh project dependencies by running:

lua crush.lua

crush fetches the project's dependencies recursively, cloning them inside a lib subdirectory. Hence, you may use them comfortably in your code with the usual require(), like this:

local serialize = require 'lib.serialize'

crush flattens every dependency in the lib folder. This implies that libraries common to different packages must be named and accessed consistently in the source code. A reasonable limitation given crush use-case.

The .lovedeps file

The .lovedeps file is a regular Lua text file, containing a table where every entry specifies a dependency:

['dependency-name'] = "git-url"

The following example shows a .lovedeps file depending on three external libraries, named df-serialize, gear and yui, every dependency has a corresponding git repository URL. There dependency name is not required to match the actual repository name, but names should be consistent within the entire project, otherwise the same repository may be cloned several times under different names.

{
    -- Fetch lib/df-serialize from https://git.doublefourteen.io/lua/df-serialize
    -- needs ['quote'] syntax due to '-'
    ['df-serialize'] = "https://git.doublefourteen.io/lua/df-serialize",

    -- Fetch lib/gear from https://git.doublefourteen.io/lua/gear
    gear = "https://git.doublefourteen.io/lua/gear",

    -- Fetch lib/yui from https://git.doublefourteen.io/lua/yui
    yui = "https://git.doublefourteen.io/lua/yui"

    -- NOTE: Any dependency may also pull additional subdependencies,
    --       these will also be cloned within lib/
}

Philosophy

crush is somehow opinionated and tied to its intended use-case. It obeys the following rules:

MUST:

• Be self-contained, only a single Lua file: crush.lua.
• Must only depend on Lua, LÖVE and git, expected to be available on any LÖVE developer machine.
• Do one thing: fetch the dependencies listed in the .lovedeps file.
• Be simple and predictable, integrating crush into a LÖVE game must be as intuitive as possible.
• Be hackable, its code must be reasonably trivial, understandable and adaptable.
• Enforce one way to do things, encouraging consistency.

MUST NOT:

• Give in to feature creep.
• Provide a centralized repository.
• Be completely general, its scope is limited to the average LÖVE game or library.
• Be entirely safe, there is no demand for checksum or strict versioning in crush use case.

SHOULD NOT:

• Break compatibility with older .lovedeps files.

If this does not meet your requirements, code should still be sufficiently hackable to provide some room for customization.

Similar projects

• LÖVERocks is a more involved project with the ambition to bring LuaRocks features to LÖVE.

License

MIT, see LICENSE for details.