Script in dependency needs path to Composer autoloader

Question

I am developing a package - myvendor/mylib - that I plan to distribute using Composer, probably via Packagist. This package contains - among other things - a commandline PHP script bin/console.php that I would like to make available to projects - say myvendor/mymain - that import the mylib package.

I am aware that I can specify in the mylib package a config setting in composer.json with an array of bins to import:

{
    "name": "myvendor/mylib",
    "config" : {
        "bin" : ["bin/console.php"]
    }
}

When the mymain project does a composer install/update, then this mylib/bin/console.php is symlinked as mymain/bin/console.php Further, I am aware that the mymain project can specify - in his own composer.json - where he wants dependency bins to be symlinked:

{
    "name": "myvendor/mymain",
    "config": {
        "bin-dir": "scripts"
    }   
}

In this case, the console script is then symlinked as scripts/console.php.

This works fine - and is cool as as all get out, by the way. ;-)

However, the script bin/console.php itself needs to include the Composer-generated vendor/autoloader.php. When developing mylib in isolation, the script bin/console.php knows his own location relative to vendor/autoloader.php, so he can include it easily. But once it is imported as a dependency into another project - myvendor/mymain, in this case - then there is only the mymain/vendor/autoloader.php script. In principle, the console script cannot know where he resides relative to that autoloader script.

Does Composer provide some environment variable - accessible to the console script - that allows the script to locate the right vendor/autoloader.php script?

BTW: I am aware of the Composer CLI environment variable, so I imagine I could make it a requirement that the importing project - mymain - define (and export!) the var COMPOSER_VENDOR_DIR. Then my console script can use that to find the project's autoloader. But that seems potentially problematic in that:

1. We want the setting to apply only to this project, but a shell var (and an export) would apply to all projects accessed from that shell session. Seems presumptuous of my little dependency - myvendor/mylib - to impose that on an importing project.

2. In principle, the dependency itself - myvendor/mylib - should be able to find what he needs. Doesn't seem right to put the onus on the importer.

WDYT? Thanks in advance. Ideas welcome.

Answer 1

One approach (that came out of discussions with @igorw on IRC freenode #composer that I am paraphrasing and on which I am somewhat expanding) is to let the bin script console.php iterate up the filesystem, starting from __DIR__, looking for the presence of autoload.php.