Re: [Usbpicprog-technical] [usbpicprog-technical] Initialization of libusb

[Frans S. <fra...@gm...>]

Hi Francesco,

On Thu, 2010-03-04 at 10:44 +0100, Francesco wrote:

> Hi Frans,
> 
> 2010/3/4 Frans Schreuder <fra...@gm...>:
> > I saw that in your modifications, you called libusb_init() from
> main.cpp (as
> > well ass libusb_exit).
> > I think it is better to move this to the hardware constructor and
> > destructor.
> hmmm, why?

Because the way it was, only the gui part was connecting to the
programmer, when the command line interface was invoked, usbpicprog gave
a seg fault. Of course it is also possible to initialize libusb twice,
but I think from hardware is more charming...

> 
> > I already tested this in linux, but I don't know if it works out
> > well on all systems?
> on Windows it didn't work well with the earlier versions of the libusb
> windows port. I didn't test recently but in any case I think that the
> initialization is a bit slow because the windows port needs to
> internally enumerate the USB hubs AFAIR.
> 
> > What was the reason for you to call these functions from main?
> in general the initialization of all libraries is done in the main()
> of a program and never repeated (as it shouldn't really be
> necessary!). The initialization routines usually allocate memory and
> perform many operations which maybe time-consuming. I don't think we
> should repeat them multiple times unless absolutely necessary.
> 
> In fact, I think that also the current organization of the Hardware
> class, which gets allocated and deleted multiple times should also be
> avoided: upp_wx currently is very slow to start up and IIRC this is
> because Hardware is created and deleted 2-3 times at the startup.
> I'd really like much more to have a
>   Hardware m_hw;
> member in UsbPicProg class definition and then have just a
>   bool Connect(HardwareType hwToTryToConnect);
> member in the Hardware class which would be used by UppMainWindow
> (only when necessary).
> 
> I think this would be:
> 1) a better design from a OOP point of view.
> 2) more efficient design => reduce startup time of upp_wx.

That's ok, in that case we can still init libusb from hardware, but only
init hardware once. 

> 
> If you agree I can do such modifications in the weekend...

I will do it myself, but I think it's a good idea.

Frans