Calibre Qt DLLs override the system Qt DLLs

Valloric · 03-10-2009, 04:49 PM

Just wanted to put this here so I spare other people the frustration. If you install calibre first and Qt second, calibre overrides the system Qt libs. This happens because calibre's path is added to the system %PATH% variable before the path to the system Qt libs.

Kovid, you could solve this by putting your Qt libs in a special folder inside calibre's folder so that they don't end up on the %PATH%. This is a good idea for most windows programs anyway.

EDIT: Oh, and this was on Windows XP.

kovidgoyal · 03-10-2009, 05:03 PM

Unfortunately, the way calibre is setup currently, it needs to have the Qt dlls on the PATH. I could probably change that if I tried hard enough, but...

Valloric · 03-10-2009, 05:12 PM

Quote:

Originally Posted by kovidgoyal

Unfortunately, the way calibre is setup currently, it needs to have the Qt dlls on the PATH. I could probably change that if I tried hard enough, but...

Well, then the only solution is to edit the PATH by hand so system Qt libs get loaded before calibre's. I did it on my system, and it's not difficult. What is difficult is finding out what was the problem in the first place. I was using Qt 4.5 for an application, and all debug builds were running fine. OTOH, the release builds crashed spectacularly.

It was not an easy thing to debug. And a windows application should not put any DLLs on the PATH if it's not bent on providing those libs to other apps... this specific issue being proof enough.

03-10-2009, 04:49 PM	#1
Valloric Created Sigil, FlightCrew Posts: 1,982 Karma: 350515 Join Date: Feb 2008 Device: Kobo Clara HD	Calibre Qt DLLs override the system Qt DLLs Just wanted to put this here so I spare other people the frustration. If you install calibre first and Qt second, calibre overrides the system Qt libs. This happens because calibre's path is added to the system %PATH% variable before the path to the system Qt libs. Kovid, you could solve this by putting your Qt libs in a special folder inside calibre's folder so that they don't end up on the %PATH%. This is a good idea for most windows programs anyway. EDIT: Oh, and this was on Windows XP. Last edited by Valloric; 03-10-2009 at 04:55 PM.

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03-10-2009, 05:03 PM	#2
kovidgoyal creator of calibre Posts: 43,850 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Unfortunately, the way calibre is setup currently, it needs to have the Qt dlls on the PATH. I could probably change that if I tried hard enough, but...

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