Porting 4.4.2 to 4.7.0

**Lykurg** · 18th October 2010, 17:31

Originally Posted by Lee B

If an older system is written with a commercial release, does that prohibit porting the system to a later LGPL version?

This way it is no problem. But if you want to change from LGPL to commercial there are some "difficulties".

Originally Posted by gboelter

Try to convert it from 4,4.2 to - let's say - 4.5 and then to 4.6 and so on.

Yeah, and don't forget to convert it first to Python, then Java, from there to Basic and then back to Qt. Seriously why do you want to do more work by stepping through older releases? That doesn't make sense. Just target 4.7 straight forward. The errors probably only because of some API changes which could be cleaned by some search&replace.

**gboelter** · 18th October 2010, 18:01

Originally Posted by Lykurg

Yeah, and don't forget to convert it first to Python, then Java, from there to Basic and then back to Qt. Seriously why do you want to do more work by stepping through older releases? That doesn't make sense. Just target 4.7 straight forward. The errors probably only because of some API changes which could be cleaned by some search&replace.

Lykurg, I know that you are good, but Lee is a beginner in Qt. If there are to many error-messages, that's very frustrating for a beginner.

So, what's wrong in doing it step by step if the project is really important for him?

I had a similar problem just a few weeks ago. To compile my source with 4.7 instead 4.6.3 was now problem under Linux. Under windows I got many error-messages.

**wysota** · 18th October 2010, 18:38

Originally Posted by gboelter

So, what's wrong in doing it step by step if the project is really important for him?

Apart from doing the same thing 10 times? Nothing, I guess. If you have a couple of evenings to spare with nothing better to do then go ahead.

The errors OP is getting are probably unrelated to the version change at all. Most likely there are some stale files in the project directory, the compiler or the environment (as in available libraries and stuff) have been changed by the project developer. In times such as this people tend to forget they installed/uninstalled/reinstalled/modified something in their system and/or project source code.

**gboelter** · 18th October 2010, 19:05

Originally Posted by wysota

The errors OP is getting are probably unrelated to the version change at all. Most likely there are some stale files in the project directory, the compiler or the environment (as in available libraries and stuff) have been changed by the project developer. In times such as this people tend to forget they installed/uninstalled/reinstalled/modified something in their system and/or project source code.

May be, may be not! I have not seen any error messages from Lee until now.

What's going on here? From what I understand, he has an application it's developed under Qt 4.4.2 and while trying to compile it under 4.7.0, he got many errors. So, what's wrong to install Qt 4.4.2 and compile the programm with that?

Later on he can try to compile it with a newer version of Qt ...

**wysota** · 18th October 2010, 19:20

Originally Posted by gboelter

May be, may be not!

Maybe they are related to the phase of the current that happened to be flowing through the power socket when he clicked the build button...

I have not seen any error messages from Lee until now.

Qt 4.7 is source-compatible with Qt 4.4.

So, what's wrong to install Qt 4.4.2 and compile the programm with that?

1. time/money spent downloading/installing/setting up Qt 4.4.2
2. no progress - he wants to build the application with 4.7 and not 4.4.
3. no relation between getting things to build with 4.4 and 4.7 - even if it builds against 4.4, it doesn't mean 4.7 incompatibility is to "blame", for example if you make some stupid mistake each time you install 4.7, the fact that your 4.4 installation works correctly will get you nowhere if you keep repeating the same mistake during each and every install of 4.7.

And between 4.4 there were also 4.5 and 4.6 and releases of each of the minor versions. This gives well over 10 installations you need to perform just to click one "build" button to see nothing has changed since the previous release.

**Lee B** · 18th October 2010, 20:20

Hi,

Thanks to everyone who has posted replies. The information given has been very helpful and thought provoking, and I will follow up the various strategies you have suggested to get the application running.
I am unable to post the exact error messages etc at the moment due to being away from the office. I will look at trying some of your ideas as soon as I get back.

Thanks again,
Lee.