...but of course on the same machine.
If I already have a QT 4.0.1 DLL installed on a machine, can I safely replace it with a QT 4.5.2 DLL? Is compatibility assured, or a matter of how lucky you are?
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...but of course on the same machine.
If I already have a QT 4.0.1 DLL installed on a machine, can I safely replace it with a QT 4.5.2 DLL? Is compatibility assured, or a matter of how lucky you are?
4.0 is not compatible with 4.5 as far as i remember.
The easiest way is to simply try :) In general it should work although the application may behave differently due to changes in the libraries.
Unfortunately, it's not as simple as that. Oh, as long as I am just a developer, tinkering around, it is. But once I start to think about deployment, things could get ugly.Quote:
Originally Posted by wysota
Consider Application Suite A, written by company X with QT 4.0
Consider Application Suite B, written by company Y with QT 4.5
If I deploy my App Suite B, I can't just ruin App Suite A by installing the new DLLs, especially when both applications are expected to work together. I also can't just "hope" that things will work with the new DLL version, this would have to be verified with (probably) weeks of testing.
If the DLLs are not compatible, Trolltech (or QT Software or whatever name they have right now) would do well to give the DLLs different names, so you can use them in parallel.
But I see this is something to discuss with them directly prior to obtaining a commercial license.
Both applications can have their own Qt libs. Just copy the version you want to be used to the directory containing the application binary and it will use it. But anyway 4.0 and 4.5 should be binary compatible (of course it won't work the other way round).
Already noticed that the hard way! :DQuote:
Originally Posted by wysota
Well... obviously classes introduced in Qt 4.5 were not present in Qt 4.0 dlls :)
Aren't Qt releases with the same major version number supposed to be compatible? So it should be possible to replace an older release with a newer one (if not, I would consider this a bug...)Quote:
Originally Posted by MrDeath
That's what I hope.Quote:
Originally Posted by rexi
No, that's true about minor version. They are binary compatible (both ways).Quote:
Originally Posted by rexi
Yes, it's possible this way (at least should be) as Qt keeps backward binary compatibility across minor versions too.Quote:
So it should be possible to replace an older release with a newer one (if not, I would consider this a bug...)
Ok, I did express myself wrong :o This was what I actually meant. I just forgot the little word "backward". Replacing an old version with a newer one should work, the other way round obviously does not, because of added features in newer versions, as you already stated.Quote:
Originally Posted by wysota