How to patch a package from another?

[boobaa]

I have a root composer.json which requires two packages, and package B depends on (requires) package A. In order to be able to use package B properly, package A needs to be patched.

How to instruct vaimo/composer-patches from package B's composer.json to patch package A? It would be the best if the root composer.json wouldn't contain these instructions.

[allanpaiste]

the format for adding patches into a package is exactly the same that you'd use in root composer.json.

So in your case package B would have this:

{
    "extra": {
        "patches": {
            "A": {
                "Compatibility: required change to create magic": "patches/compatibility-with-dependency-a.patch"
            }
        }
    }
}

... where you'd have /patches/compatibility-with-dependency-a.patch and paths in patch are relative to the root of package A.

Note that you can test it out if you have the composer-patches module installed and execute...

composer patch --redo --from-source --filter compatibility-with-dependency-a

The 'filter' part is really optional as you could also try to re-apply everything. the 'from-source' makes the patches scan for patches directly in 'vendor' folder (which allows patches to be pre-tested before [updating/commiting changes to] a given package). The default behaviour is to scan for them in installed.json

[boobaa]

Thanks for your quick answer, works like a charm! Could it also be added to the documentation, please? :)

[allanpaiste]

I'm glad that you got it working :) Added this Q/A as an example to the readme + clarified where the definition format can be used @ 554abba