PythonQtObjectPtr::evalScript() question

[johnw]

Hi, I'm having trouble getting a value returned from evalScript(). I have the following C++ code:

PythonQtObjectPtr _delegate;
_delegate = APLab::instance()->aplabModule.evalScript("APLab.newDirectoryModelDelegate()");

and Python code:

def newDirectoryModelDelegate():
    from directory.directory_pane import DirectoryItemModelDelegate
    return DirectoryItemModelDelegate(directory)

the returned PythonQtObjectPtr always has a 0 pointer in it. However, if I change the Python code to:

def newDirectoryModelDelegate():
    global directoryModelDelegate
    from directory.directory_pane import DirectoryItemModelDelegate
    directoryModelDelegate = DirectoryItemModelDelegate(directory)

and C++ to:

APLab::instance()->aplabModule.evalScript("APLab.newDirectoryModelDelegate()");
_delegate = APLab::instance()->aplabModule.getVariable("directoryModelDelegate");

I get a good PythonQtObjectPtr. Shouldn't evalScript() return the value of the function call in the first case? I also tried capturing the function result in a module variable prior to returning the function result, in case of refCount issues, but same error.

Any suggestions, I'd rather not use that thread-unsafe hack?

Thanks,
John.

[Florian Link]

You need to pass Py_eval_input as second parameter to evalScript(). Note that then you can only pass a single expression as source code.

The reason is that Python code does not automatically return the last value as its result, only expressions do that.

Alternatively, you can do:

PythonQtObjectPtr _delegate;
_delegate = APLab::instance()->aplabModule.call("APLab.newDirectoryModelDelegate");

to call the method and get the result.

[johnw]

OK, thanks Florian, that fixed it!