[Interest] Support for multiple 'out' parameters in qdbusxml2cpp

[Thiago Macieira]

On sexta-feira, 26 de julho de 2013 15:27:21, Matt Hoosier wrote:
> I've observed that qdbusxml2cpp doesn't emit the QMetaCall that would
> forward a D-Bus method-call message from the adaptor along to the "business
> logic" class that provides slots to implement all the various methods.
> E.g., if I have:
> 
>   <method name="Foo">
>     <arg name="inValue" direction="in" type="s"/>
>     <arg name="outValue1" direction="out" type="s"/>
>     <arg name="outValue2" direction="out" type="s"/>
>   </method>
> 
> the adaptor code for this method ends up looking like:
> 
>   ...
>   public Q_SLOTS:
>     QString MyInterfaceAdaptor::Foo(const QString &inValue, QString
> &outValue2)
>     {
>         // handle method call MyInterfaceAdaptor.Foo
>         //return static_cast<YourObjectType *>(parent())->Hello(inValue,
> outValue);
>     }
> 
> Is there a design reason behind this? I examined the source to
> qdbusxml2cpp, and it doesn't give any rationale why this type of call isn't
> marshaled through a QMetaObject::invokeMethod() call the same as the
> others. Passing the additional 'out' parameters as by-ref variables would
> seem straightforward enough.

Hi Matt

According to the source code, the comment comes from:

                if (parentClassName.isEmpty())
                    cs << "    //";
                else
                    cs << "    ";

and it later shows:
                if (parentClassName.isEmpty())
                    cs << "static_cast<YourObjectType *>(parent())->";
                else
                    cs << "parent()->";

The presence of "YourObjectType" in the output you pasted to us confirms the 
analysis.

The reason why it's commented out is that you didn't tell qdbusxml2cpp what 
the parent class type is. It can't write the code that will make the call 
without that information.

You should pass the -l argument to qdbusxml2cpp, which sets the parent class 
name. (option -c was taken to mean the name of the class that qdbusxml2cpp is 
generating and -p was taken to mean the name of the file for the "proxy" class, 
which is the old name for what we now call the "interface" class).

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center
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