what's meant by "Charge for development licenses"

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+2 Q:

what's meant by "Charge for development licenses"

Hi I was downloading Qt creator IDE and they say "Charge for development licenses" with a (True) under Commercial and (FALSE) under LGPL.

Also I need to know something general About QT library. is it free so I can make (commercial products and sell ) or I will have to buy something to do that.

EDIT: the page is Actually about QT the library and at the page end is the QT creator the IDE and I'm confused now does this mean I get to use QT creator IDE for free and if I make apps without the QT library it's ok ? total free ? cause that's what I want , I just need the IDE .. not the QT library SDK

It means that the product is free for all non-commercial use under the LGPL (Lesser Gnu Public License), but for commercial purposes you must pay for a license.

DJ Quimby 2010-10-29 16:08:10

what If i'm not going to use Qt libraries in the first place, and just the IDE ?

ismail marmoush 2010-10-29 16:10:16

@Ismail: Good question, maybe update your original question?

FrustratedWithFormsDesigner 2010-10-29 16:12:07

yes I was actually doin that :D

ismail marmoush 2010-10-29 16:14:20

What with commercial licenses? LGPL is NOT the Gnu Public License, it is the LESSER (!) Gnu Public License that allows me to link with LGPL compiled code FROM A CLOSED SOURCE APP.

TomTom 2010-10-29 16:15:41

@TomTom My bad, should have looked up the acronym first.

DJ Quimby 2010-10-29 16:29:03

As the page in question says, your options are:

Pay and allow closed source program distribution (i.e. non-LGPL license)
Get it free and your software must be open source (as imposed by the use of the LGPL license).

So basically, if you sell your program and bundle the source code, you can still use Qt without paying, but that might not be what you have in mind.

In any case, if you're talking about commercializing a real product for a real business, you will really want to discuss this with a lawyer, not programming experts.

André Caron 2010-10-29 16:09:00

But... LGPL allows me to kep my app closed source. THis is the whole reason to go with LGPL instead of GPL - the use of compiled libararies in closed source systems.

TomTom 2010-10-29 16:15:06

**If** I remember correctly (haven't re-read it in a while), LGPL allows you to keep your program closed source if the program can run without the use of the LGPL library. This would mean that implementing a dynamically-loaded plugin using an LGPL library would not force you to re-distribute sources of the host application. However, I doubt that is how you plan to use Qt. Again, consult with your **lawyer** to make sure you don't get any nasty surprises.

André Caron 2010-10-29 16:19:41

To clarify my last comment... basically, if your application has a *strong dependence* on the LGPL library (i.e. removing it means you cannot compile or core functionality is removed), it is considered a derived work. All derived works *must* be re-distributed along with LGPL source code.

André Caron 2010-10-29 16:21:55

Ah - no. Check it. It is VERY clealry explained both ag GNU as well as Wikipedia. You can LINK it to non-GPL software, which is why it is LESSER.

TomTom 2010-10-29 16:22:45

+3 A:

That page is a summary with slightly odd wording - perhaps somebody whose first language wasn't english or something got edited down to fit a bullet point
It also dates from before there was the change from GPL to LGPL for the Qt libs.

See http://qt.nokia.com/products/licensing for the full details

The table doesn't format here but it specifically states you can use the LGPL version to build proprietry software. The only requirement is that under the LGPL any changes to Qt itself must be redistributed.

Outside the scope of the question but the LGPL means that you can link a propriety app with an LGPL library as long as the user can swap out the LGPL lib for their own. This normally means linking the lib dynamically (ie .so or .dll) but can also mean statically linking but offering to supply your object code so that it can be relinked (this is rare).

See http://www.gnu.org/licenses/lgpl-2.1.html sections 5 and 6, especially 6b

Martin Beckett 2010-10-29 16:36:08

logical answer! thanks alot man

ismail marmoush 2010-10-29 16:52:04

If you are only using the Qt IDE (QtCreator) and not otherwise using Qt or linking to the Qt libraries, then you can use the IDE for free to create commercial programs.

PiedPiper 2010-10-29 16:52:08

yes tht's it :)

ismail marmoush 2010-10-29 17:00:40

ansaurus

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what's meant by "Charge for development licenses"

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