How to represent void pointer in PyObjC selector?

Question

I want to use NSOpenPanel for the application that I am developing. Here is what I still have:

@objc.IBAction
def ShowOpenPanel_(self, sender):
    self.panel = NSOpenPanel.openPanel()
    self.panel.setCanChooseFiles_(False)
    self.panel.setCanChooseDirectories_(True)
    NSLog(u'Starting OpenPanel')
    self.panel.beginForDirectory_file_types_modelessDelegate_didEndSelector_contextInfo_(
        self.defaults.objectForKey_(u'projpath'), 
        objc.nil, 
        objc.nil, 
        self, 
        objc.selector(self.OpenPanelDidEnd_returnCode_contextInfo_, 
            signature='v:@ii'),
        objc.nil)
    NSLog(u'OpenPanel was started.')

def OpenPanelDidEnd_returnCode_contextInfo_(self, panel, returnCode, context):
    NSLog('Panel ended.')
    if (returnCode == NSOKButton):
        NSLog(u'User selected OK')
        path = self.panel.filenames()[0]
        self.defaults.setObject_forKey_(path, u'projpath')
    del self.panel

The main two lines I'm worried about are:

        objc.selector(self.OpenPanelDidEnd_returnCode_contextInfo_, 
            signature='v:@ii'),
        objc.nil) #this is the argument that gets passed as the void pointer

The third argument should be a pointer to void. Since I am not going to use this data, I would prefer to leave it blank. I tried to sign 'v:@iv'and tried to use objc.NULLboth python Noneand almost every combination of all these things. What is the best way to handle this?

Answer 1

, objc.selector; :

@objc.IBAction
def ShowOpenPanel_(self, sender):
    self.panel = NSOpenPanel.openPanel()
    self.panel.setCanChooseFiles_(False)
    self.panel.setCanChooseDirectories_(True)
    NSLog(u'Starting OpenPanel')
    self.panel.beginForDirectory_file_types_modelessDelegate_didEndSelector_contextInfo_(
        self.defaults.objectForKey_(u'projpath'), 
        objc.nil, 
        objc.nil, 
        self, 
        self.OpenPanelDidEnd_returnCode_contextInfo_,
        objc.nil)
    NSLog(u'OpenPanel was started.')

, PyObjCTools.AppHelper.endSheetMethod:

@PyObjCTools.AppHelper.endSheetMethod
def OpenPanelDidEnd_returnCode_contextInfo_(self, panel, returnCode, context):
    NSLog('Panel ended.')
    if (returnCode == NSOKButton):
        NSLog(u'User selected OK')
        path = self.panel.filenames()[0]
        self.defaults.setObject_forKey_(path, u'projpath')
    del self.panel

, :

@objc.IBAction
def showOpenPanel_(self, sender):
    panel = NSOpenPanel.openPanel()
    panel.setCanChooseFiles_(False)
    panel.setCanChooseDirectories_(True)
    NSLog(u'Starting openPanel')
    panel.beginForDirectory_file_types_modelessDelegate_didEndSelector_contextInfo_(
        self.defaults.objectForKey_(u'projpath'),    #forDirectory
        None,    #file
        None,    #types
        self,    #modelessDelegate
        self.openPanelDidEnd_returnCode_contextInfo_,    #didEndSelector
        None)    #contextInfo
    NSLog(u'openPanel started')

@PyObjCTools.AppHelper.endSheetMethod
def openPanelDidEnd_returnCode_contextInfo_(self, panel, returnCode, context):
    NSLog(u'Panel ended')
    if returnCode != NSOKButton:
        return
    NSLog(u'User selected OK')
    path = panel.filenames()[0]
    self.defaults.setObject_forKey_(path, u'projpath')

: None, objc.nil, ; , self, ; objc - .

Answer 2

:

@objc.IBAction
def showOpenPanel_(self, sender):
    panel = NSOpenPanel.openPanel()
    panel.setCanChooseFiles_(False)
    panel.setCanChooseDirectories_(True)
    NSLog(u'Starting openPanel')
    panel.beginForDirectory_file_types_modelessDelegate_didEndSelector_contextInfo_(
        self.defaults.objectForKey_(u'projpath'),    #forDirectory
        None,    #file
        None,    #types
        self,    #modelessDelegate
        'openPanelDidEnd:returnCode:contextInfo:',    #didEndSelector
        None)    #contextInfo
    NSLog(u'openPanel started')

, IMHO : , , .