README

Provides a metapackage for library needing psr/http-message-implementation that fallback to a default implementation when user does not meet the initial requirements.

Usage

composer require "Neur0toxine/psr.http-message-implementation.nyholm:*"

Composer will, by preference:

• use an implementation provided by the user
• otherwise, fallbacks to nyholm/psr7

How does it works

This package contains 2 versions:

1. The highest 1.1 needs nothing more than your requirements.

2. The lowest 1.0 triggers install of nyholm/psr7.

Composer will choose this highest version when user already has a package that satisfy psr/http-message-implementation. Otherwise, composer will choose the lowest version and in that case will download the following packages: nyholm/psr7.

What problem does it solve?

You are maintaining a library that need an implementation of psr/http-message-implementation, but you don't want requiring a specific implementation.

ie. You are maintainer of library that use the following composer.json

{
  "name": "acme/lib",
  "require": {
    "psr/http-message-implementation": "^1.0",
  }
}

When end users requires you library with the following code

{
    "name": "end-user/app",
    "require": {
      "acme/lib": "^1.0"
    }
}

They probably ends with such error

composer up

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for acme/lib ^1.0 -> satisfiable by acme/lib[1.0].
    - acme/lib 1.0 requires psr/http-message-implementation ^1.0 -> no matching package found.

You can ask user to install a random package, it works, but the DX is very bad, and confusing at first.

By using Neur0toxine/psr.http-message-implementation.nyholm, users will be able to require their preferred implementation or fallback to your default choice

Example of user that meet the preferred requirements

{
    "name": "end-user/app",
    "require": {
        "acme/lib": "^1.0",
        "third-party/provide-implementation": "^1.0"
    }
}

composer up
...
Package operations: 2 installs, 0 updates, 0 removals
  - Installing acme/lib (1.0)
  - Installing Neur0toxine/psr.http-message-implementation.nyholm (1.1)

Example of user that fallback to your recommendations

{
    "name": "end-user/app",
    "require": {
        "acme/lib": "^1.0"
    }
}

composer up
...
Package operations: 3 installs, 0 updates, 0 removals
  - Installing acme/lib (1.0)
  - Installing Neur0toxine/psr.http-message-implementation.nyholm (1.0)
  - Installing nyholm/psr7 (1.0)

Contributing

This repository is automatically generated. If you want contributing and submitting an issue or a Pull Request, please use composer-fallback/generator.