pyobjc-dev

[Pyobjc-dev] problem with NSTableView

[chris b. <por...@ya...>]

Hello, I'm currently experiencing an error with my
program which lead to the following getting outputted
to the console

2003-03-07 21:14:33.618 whisper[508] Application did
finish launching.
2003-03-07 21:15:09.902 whisper[508] *** Assertion
failure in -[NSTableView _locationOfRow:],
TableView.subproj NSTableView.m:486
2003-03-07 21:15:10.028 whisper[508]
NSInternalInconsistencyException

I haven't actually been able to find the
_locationOfRow: method in any of Apple's documentation
or the web. I guess it must be a private call to do
with the way that the object renders itself to screen.
So if any of you know what this actually is so I can
figure out what is going wrong that would be very
useful.

I'm programming in Python and bridging to Cocoa with
the PyObjC module (version 0.8). This NSTableView
instance is pure Obj-C and was created via Interface
builder.

The error occurs when setting the datasource of the
NSTableView object using the following Python code.

self.knownEntitiesTable.setDataSource_(self.knownEntities)

self.knownEntities is a Python object that inheriting
from NSObject and implementing the informal
NSTableDataSource protocol. At this point it contains
no data to display as I'm just setting the program up
at this point.

Any help that you can give would be greatly
appreciated. Thanks in advance.

Chris

here is the python code of the knownEntities Object
that acts as the datasource.

class entityTable(NSObject):
    identitiesList = []
    counter = 0
        
    def numberOfRowsInTableView_(self):
        NSLog(str(self.counter))
        return self.counter
        
    def tableView_objectValueForTableColumn_row_(self,
tableView, tableColumn, row):
        NSLog(self.identitiesList[row].name)
        return self.identitiesList[row].name
        
    def
tableView_setObjectValue_forTableColumn_row_(self,
tableView, id, tableColumn, row):
        self.identitiesList.insert(row,id)
        
    def setIdentity(self,id,row):
        if row < len(self.identities):
            self.identitiesList[row] = id
        else:
            self.identitiesList.append(id)
        self.counter += 1
    
    def setIdentities(self,ids):
        self.counter = len(ids)
        self.identitiesList = ids
        
    def getIdentity(self,row):
        return self.identitiesList[row]
        
    def getIdentities(self):
        return self.identitiesList
        
    def append(self,id):
        self.counter += 1
        self.identitiesList.append(id)
        
    #it has been very insistent about these two
methods
    def __len__(self):
        return self.counter
        
    def __getitem__(self, key):
        return self.identitiesList[key]

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Re: [Pyobjc-dev] problem with NSTableView

[<bo...@pa...>]

there are issues right off the bat that you will need to
resolve:

first, declare the "informal" protocol NSTableDataSource, like
this:

	class entityTable(AutoBaseClass, NSTableDataSource):

second, there are enough bugs in 0.8 with NSTables, that you are better
off building from scratch out of the CVS depot. make sure you build FFI
first and follow the FFI build/install instructions exactly [especially
the part about creating and cd'ing into the build directory].

--bob



On Thursday, March 13, 2003, at 11:56 AM, chris bunker wrote:

> Hello, I'm currently experiencing an error with my
> program which lead to the following getting outputted
> to the console
>
> 2003-03-07 21:14:33.618 whisper[508] Application did
> finish launching.
> 2003-03-07 21:15:09.902 whisper[508] *** Assertion
> failure in -[NSTableView _locationOfRow:],
> TableView.subproj NSTableView.m:486
> 2003-03-07 21:15:10.028 whisper[508]
> NSInternalInconsistencyException
>
> I haven't actually been able to find the
> _locationOfRow: method in any of Apple's documentation
> or the web. I guess it must be a private call to do
> with the way that the object renders itself to screen.
> So if any of you know what this actually is so I can
> figure out what is going wrong that would be very
> useful.
>
> I'm programming in Python and bridging to Cocoa with
> the PyObjC module (version 0.8). This NSTableView
> instance is pure Obj-C and was created via Interface
> builder.
>
> The error occurs when setting the datasource of the
> NSTableView object using the following Python code.
>
> self.knownEntitiesTable.setDataSource_(self.knownEntities)
>
> self.knownEntities is a Python object that inheriting
> from NSObject and implementing the informal
> NSTableDataSource protocol. At this point it contains
> no data to display as I'm just setting the program up
> at this point.
>
> Any help that you can give would be greatly
> appreciated. Thanks in advance.
>
> Chris
>
> here is the python code of the knownEntities Object
> that acts as the datasource.
>
> class entityTable(NSObject):
>     identitiesList = []
>     counter = 0
>
>     def numberOfRowsInTableView_(self):
>         NSLog(str(self.counter))
>         return self.counter
>
>     def tableView_objectValueForTableColumn_row_(self,
> tableView, tableColumn, row):
>         NSLog(self.identitiesList[row].name)
>         return self.identitiesList[row].name
>
>     def
> tableView_setObjectValue_forTableColumn_row_(self,
> tableView, id, tableColumn, row):
>         self.identitiesList.insert(row,id)
>
>     def setIdentity(self,id,row):
>         if row < len(self.identities):
>             self.identitiesList[row] = id
>         else:
>             self.identitiesList.append(id)
>         self.counter += 1
>
>     def setIdentities(self,ids):
>         self.counter = len(ids)
>         self.identitiesList = ids
>
>     def getIdentity(self,row):
>         return self.identitiesList[row]
>
>     def getIdentities(self):
>         return self.identitiesList
>
>     def append(self,id):
>         self.counter += 1
>         self.identitiesList.append(id)
>
>     #it has been very insistent about these two
> methods
>     def __len__(self):
>         return self.counter
>
>     def __getitem__(self, key):
>         return self.identitiesList[key]
>
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Re: [Pyobjc-dev] problem with NSTableView

[<bb...@ma...>]

On Thursday, Mar 13, 2003, at 14:56 US/Eastern, chris bunker wrote:
....
> self.knownEntities is a Python object that inheriting
> from NSObject and implementing the informal
> NSTableDataSource protocol. At this point it contains
> no data to display as I'm just setting the program up
> at this point.
>
> ....
> class entityTable(NSObject):
...

Change the declaration to:

> class entityTable(NSObject, NSTableDataSource):

(BTW:  Normally, that class would be called 'EntityTable' to be 
consistent w/ObjC and Python naming conventions.)

--

When implementing one of the informal protocols, you need to 
specifically declare [in Python] that you are doing so.  This allows 
PyObjC to figure out the correct types for the arguments to the method. 
   The alternative is to use the objc.selector() function to declare the 
appropriate types on the methods -- but that is considerably more 
tedious.

I posted a relatively long message a few days [weeks?] ago that 
explains informal protocols and their implementation in Python via 
PyObjC -- see the list archives.

b.bum
(Stuck in Cocoa/Java land right now.... makes me appreciate 
Cocoa/Python all the more)

Re: [Pyobjc-dev] problem with NSTableView

[Ronald O. <ous...@ci...>]

On Thursday, Mar 13, 2003, at 20:56 Europe/Amsterdam, chris bunker 
wrote:

> Hello, I'm currently experiencing an error with my
> program which lead to the following getting outputted
> to the console


> here is the python code of the knownEntities Object
> that acts as the datasource.
>
> class entityTable(NSObject):

There's your problem. You should also inherit from NSTableDataSource:

	class entityTable(NSObject, NSTableDataSource):
		...

This is necessary to make sure that the bridge knows the right method 
signatures for Objective-C: A number of the methods in the datasource 
protocol use plain C types as arguments or return value, without this 
hint the bridge assumes that all arguments and return values are 
objects.

Ronald

Re: [Pyobjc-dev] problem with NSTableView

[Martina O. <Ma...@Oe...>]

Hi Chris,

> here is the python code of the knownEntities Object
> that acts as the datasource.
>
> class entityTable(NSObject):
>
change this to:

	from AppKit import NSTableDataSource
	class entityTable(NSTableDataSource):

PyObjc needs to know the method signatures (parameter and return 
types). If it doesn't know them it assumes they are of type ID, which 
causes the crash.

The NSTableDataSource class declares the proper method signatures 
signatures for you.

ciao
Martina