[Interest] Usable Qt [Was: download a file form http]

Harri Pasanen harri at mpaja.com
Thu Jul 5 12:51:41 CEST 2012

So what's wrong with QtSDK/Examples/4.7/network/download/main.cpp?

It is a complete example in Qt, all in one file, 175 lines only.

It gives a complete class which can be used with one line:


Of course it would be nice to have this documented and part of the 
standard lib, with some added features.

But as far as C++ code to do downloads it is pretty simple.  It would 
even be trivial to add QML wrapper for the DownloadManager class.


On 07/05/2012 11:32 AM, Sivan Greenberg wrote:
> Thanks Tony. With your help, is there a way to download a file using
> Qt, remain dependent only on Qt, and support multiple targets without
> having to create your own custom build scripts, reading qmake's code,
> finding alternative build system, reading QNAM's code (which I
> actually did) , spawning a python subprocess to do the actual
> downloading, and so forth?
> I'd  really just like to concentrate on my application logic and have
> a demo that downloads one file from a web service[0] real quick e.g.
> "rapid prototyping and POC". Perhaps this way of using Qt is not in
> par with the framework's nature and design; read: one has to become a
> Qt expert for a few years before achieving such a task?
> Or perhaps, and this is very valid argument, Qt is for those who
> really know what they are doing, and given my questions- I certainly
> do not, so should I revert to use Python/GTK which is my original
> expertise?
> Now, I am genuinely asking to create discussion and try to improve -
> If this is usable by others, I'd love us to think up a class for
> "humane" interface and be interested in contributing it (e.g. more
> high level operations like WebDAV/REST web or similar to)  to network
> operations which are now days pivotal in importance given cloud
> technology takes over.
> If Qt is not suitable for rapid prototyping, then I apologize for the
> noise, but I think if Qt is to survive forward we must follow suite
> with the rest of the industry and make network operations as easy[1]
> as creating a widget, IMHO. In general we need to make the common
> stuff easy, and the complex possible[2].
>   That is if we claim to provide a "Generic application development
> framework that enables you to code once, deploy everywhere". There is
> no issue in being a niche technology with limited focus, but we must
> communicate this loudly and strongly so people making business
> decision upon our code will know exactly what they are "paying" or be
> able to pay only for what they eat[3].
> Also note, that drilling Google does not come with useful snippets to
> use, but then you could argue someone has to know how to use Google as
> well...
> If my tone sounds a bit harsh, or inappropriate I do apologize as
> everybody around here knows how much I absolutely love this project,
> its people and community and defend it furiously  myself against Nay
> Sayers that approached me with this exact issue and argument. But I do
> believe, that if we are to survive to next years of computing this
> kind of discussions and re-steering of the bowl by "new blood" in the
> community is crucial for the future.
> Thanks for you attention, and sorry for the long email!
> -Sivan
> ----
> [0]: https://gitorious.org/cquick#more
> [1]: Downloading a file in python:
> 'import urllib
> urllib.urlretrieve ("http://www.example.com/songs/mp3.mp3", "mp3.mp3")'
> [2]: http://en.wikipedia.org/wiki/Perl_6#History
> "In Perl 6, we decided it would be better to fix the language than fix
> the user" -Larry Wall. (reading the whole "History" paragraph would
> bring more insight so is a *very* recommended read).
> [3]: http://docs.pylonsproject.org/projects/pyramid/en/1.0-branch/narr/introduction.html
> "Pyramid takes a “pay only for what you eat” approach. This means that
> you can get results even if you have only a partial understanding of
> Pyramid."
> In that sense, I do not want to have to be HTTP and network expert to
> be able to download a file.
> On Thu, Jul 5, 2012 at 11:41 AM, Tony Rietwyk <tony at rightsoft.com.au> wrote:
>>> Sent: Thursday, 5 July 2012 6:03 PM
>>> Thanks for all of the replies, how do I then make the MOC step happen
>>> before everything else in Qt creator or by plainly using qmake?
>>> (letting qmake "do the right thing" did not work).
>>> Thanks again!
>>> -Sivan
>> It depends on your tool-chain, and how you created the build scripts.
>> I use hand-edited .pro (and .pri) files, and run qmake to generate Visual
>> Studio  and Xcode project files.
>> There is an option for qmake to create a .pro file, but I've never used it.
>> Tony.
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