Hi Ulf, thanks for clarifying. You're absolutely right, no other language supports importing different versions of dependencies but I think it is a great feature of QML that helps a lot in maintaining the old code. Would be sad to see it gone in QML 3.
Cheers PS I'm forwarding this email to the mailing list again, apparently I didn't manage to this right in the first place On Thu, Nov 21, 2019 at 4:23 PM Ulf Hermann <ulf.herm...@qt.io> wrote: > > Suppose it's been a while, and your customer has used this library in > > their code in 100 QML files. Now you enhance/refactor your library and > > you decide that the name `popupSource` was not really good because it > > clashes with a new component, so you change it to `componentSource` in > > the new version: > > This is a compatibility breaking change. There is no way a QML program > written against the old version of your library will work with the new > version of your library without modification. You should use a new major > version for this. The minor versions were intended for non-breaking > changes, specifically for adding properties, methods, enums. If you > avoid unqualified lookup you can do these things without special > consideration in the customers of your library, as they won't see the > new constructs unless they explicitly look them up. > > We might also remove the major version, though. The cleanest way to > upgrade your library's clients to a new version of your library is not > providing both versions of the QML code in one version of your library, > but rather releasing a completely new library with only new code, and > adapting your client code to use that. Currently you can do that on a > file-by-file basis, but allowing that was a mistake. You should port the > client code at least on a module-by-module basis, so that you can use > the same version of your dependencies in each file. No other language I > know allows you to import different versions of a dependency in two > files of the same module. > > You may need some migration strategy, like providing deprecated > properties for a while in order to ease transition. This is pretty much > the same as in C++, then. > > Ulf >
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