[Development] QML import versions
416365416c at gmail.com
Mon Sep 21 19:51:18 CEST 2015
On Mon, Sep 21, 2015 at 3:36 AM, Hausmann Simon
<Simon.Hausmann at theqtcompany.com> wrote:
> I agree that something "new" needs to be put on the table in order to solve
> this. And "this" expands unfortunately to a few issues at the same time.
> I think that it would be a mistake of "import QtQuick" - without any version
> tag - would always import the latest available
> version on the system. If we look into other development communities with
> package based environments such as Python (pip)
> or Go, then we can see that the approach of automatically always importing
> the latest version is known to cause more headaches
> than do good. Very quickly the users want to be able to _pin_ to a certain
> version and be themselves in control when to "upgrade"
> to newer API.
> I think that we should learn from this and this is why I think generally
> applying a version to the QML APIs is a good thing. I believe that what
> we are missing is the convenience of making the conscious step of changing
> the of QtQuick 2.4 to 2.5 - it is incredibly tedious at this
> point as it requires touching every single file.
I still don't know why people feel they need to do this. Touch the
files that you want
to use new features in, and if the others are importing a different
minor version that's
okay. Then the work is only marginally bigger than the actual new
feature work in your
application. A big point of the QML versioning system is that multiple
imports of the
same module can co-exist happily in the same engine.
> Therefore I think that we should introduce the notion of configuration files
> that apply to an entire project. For QML modules that configuration
> file is the qmldir file, although I'd prefer something different. For
> applications - the primary target audience in this thread - we are lacking a
> central place where we could say that
> import QtQuick
> should resolve to exactly version 2.4.
> In other words: I think we should allow application developers to use just
> "import QtQuick" in their qml files - without a version. But all that
> should mean is that when the engine encounters a version-less import, it
> should look for the project configuration file to pick the version the
> developer would like to choose.
Since we don't have an existing central place for where to look, I
think this connection isn't obvious in the code (where it should be
easily readable). I like the concept though, maybe it could be "import
QtQuick from Project" or "import QtQuick from ../project.qmldir" to
give a direct link to the program configuration file.
An explicit file link would also help with modules, which presumably
need to package their import versions and use them instead of the
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