instanceof considered harmfull and results to error : Link does not extend ApolloLink and implement request about apollo-link

[jbaxleyiii]

This is removed in the new version!

[Aetherall]

Same error here

[slightlytyler]

@PCreations @Aetherall don't use apollo-link-core. instead install [email protected] directly and import from the there instead. the upgrade docs need to be updated to reflect this

[PCreations]

@slightlytyler It doesn't change anything for me. Look at the repos I linked above, I updateed the dependency but still the same problem. Maybe It has something to do with the way I bundle the package with rollup ?

[PCreations]

Ok I found the issue I think. Using instanceof is not safe, and considered a code smell and harmfull. We should favor duck typing instead. instanceof can be buggy when dependencies are not correctly linked together and ends up being "loaded" twice (even if it's the same version). This can happen when linking a package when developping locally. That's what I did with a yarn link command. Publishing the package to npm solved the issue but we should definitively avoid using instanceof I think.