pyobjc-dev

[Pyobjc-dev] shouldSelectRow not working as expected

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

well, my tableview_shouldSelectRow is being called, but somehow the
return value is getting ingored on the way back to the TableView.

here's my delegate code, which hopes to make every other row selectable.
it prints the results, but every row in the table is still selectable.
changing it to return 0 doesnt help.

     def tableView_shouldSelectRow_(self, aTableView, rowIndex):
		print "shouldSelectRow %d is %d" % (rowIndex, rowIndex % 2)
          return rowIndex % 2

so, i made the same change to TableModel2, and that didn't produce
the expected behavior, either.

then, i took this sample objC NSTableView code

	http://www.macdevcenter.com/pub/a/mac/2002/08/27/cocoa.html

wired up the controller as a delegate and added

- (BOOL)tableView:(NSTableView *)aTableView 
shouldSelectRow:(int)rowIndex
{
     if (rowIndex % 2) {
         return YES;
     } else {
         return NO;
     }
}

and this of course works correctly.

any ideas?

--bob

Re: [Pyobjc-dev] shouldSelectRow not working as expected

[Chris R. <cp...@em...>]

Bob--

Perhaps the BOOL return value is really what's needed, so you need to 
return YES or NO?

On Thursday, February 27, 2003, at 07:52  PM, Bob Pasker wrote:
>     def tableView_shouldSelectRow_(self, aTableView, rowIndex):
> 		print "shouldSelectRow %d is %d" % (rowIndex, rowIndex % 2)
>          return rowIndex % 2

Try

             return (rowIndex % 2) == 1

which should normalize to a true boolean value, or, perhaps more safely 
(is it necessary?),

             if (rowIndex % 2) == 1
                 return YES
             else
                 return NO

(or, if the latest conditional expression PEP gets approved ;-),

             return if (rowIndex % 2 == 1): YES else: NO

Cheers!
--Chris Ryland / Em Software, Inc. / www.emsoftware.com

Re: [Pyobjc-dev] shouldSelectRow not working as expected

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

Hi Chris,

good suggestion. i enabled column selection in IB, and this delegate 
method still
runs and still permits column selecting.

     def tableView_shouldSelectTableColumn_(self, aTableView, 
aTableColumn):
         print "select table?"
         return 0==1

i think there's something wrong with the call linkages for boolean 
return types, but
i can't figure out what it is. if anybody else can get this to actually 
work on
TableModel2,  i'd be interested to know how.

--bob

On Thursday, February 27, 2003, at 07:17 PM, Chris Ryland wrote:

> Bob--
>
> Perhaps the BOOL return value is really what's needed, so you need to 
> return YES or NO?
>
> On Thursday, February 27, 2003, at 07:52  PM, Bob Pasker wrote:
>>     def tableView_shouldSelectRow_(self, aTableView, rowIndex):
>> 		print "shouldSelectRow %d is %d" % (rowIndex, rowIndex % 2)
>>          return rowIndex % 2
>
> Try
>
>             return (rowIndex % 2) == 1
>
> which should normalize to a true boolean value, or, perhaps more 
> safely (is it necessary?),
>
>             if (rowIndex % 2) == 1
>                 return YES
>             else
>                 return NO
>
> (or, if the latest conditional expression PEP gets approved ;-),
>
>             return if (rowIndex % 2 == 1): YES else: NO
>
> Cheers!
> --Chris Ryland / Em Software, Inc. / www.emsoftware.com
>

Re: [Pyobjc-dev] shouldSelectRow not working as expected

[Just v. R. <ju...@le...>]

Bob Pasker wrote:

> good suggestion. i enabled column selection in IB, and this delegate 
> method still
> runs and still permits column selecting.
> 
>      def tableView_shouldSelectTableColumn_(self, aTableView, 
> aTableColumn):
>          print "select table?"
>          return 0==1

I've seen similar things: the only way I could force a false BOOL value
was to return None. I think this is a bug.

Just

Re: [Pyobjc-dev] shouldSelectRow not working as expected

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

On Friday, Feb 28, 2003, at 09:52 Europe/Amsterdam, Just van Rossum 
wrote:

> I think this is a bug.

Right. Does the patch I just checked in solve the problem?

Ronald

Re: [Pyobjc-dev] shouldSelectRow not working as expected

[Just v. R. <ju...@le...>]

Ronald Oussoren wrote:

> Right. Does the patch I just checked in solve the problem?

Partly, it seems. However, you _must_ return an int/bool for methods
that are declared to return a BOOL; when I return None instead I get an
exception. I assume that's because ObjC can't see the difference between
a BOOL and a char at the time the conversion happens.

In my PythonBrowser playground I have an inconsitency, though. Two
methods are supposed to return BOOLs, yet one is part of the
NSOutlineViewDataSource protocol, the other is an NSOutlineView delegate
method (is there even a NSOutlineViewDelegate protocol?).

class PythonBrowserModel(AutoBaseClass, NSOutlineViewDataSource):

    [..snippo..]

    def outlineView_isItemExpandable_(self, view, item):
        # part of the NSOutlineViewDataSource protocol,
        # must return int/bool
        if item is None:
            item = self.root
        return item.isExpandable()

    def outlineView_shouldEditTableColumn_item_(self, view, col, item):
        # this is a delegate method of NSOutlineView, I _must_ return
        # None as "NO", any other object as "YES", hence the "or None"
        # hack.
        return item.isEditable() or None

I suppose this is not solvable without adding an NSOutlineViewDelegate
informal protocol?

Here's a thought: what if the bridge would convert the False bool
instance to nil? Hm, this would only work with Python 2.3 unless we add
proper bool support to 2.2 ourselves (btw. plistlib.py contains code
that does just that, but only for that module).

Just

Re: [Pyobjc-dev] shouldSelectRow not working as expected

[Just v. R. <ju...@le...>]

Just van Rossum wrote:

> Here's a thought: what if the bridge would convert the False bool
> instance to nil? Hm, this would only work with Python 2.3 unless we
> add proper bool support to 2.2 ourselves (btw. plistlib.py contains
> code that does just that, but only for that module).

I just tried, and this indeed works for 2.3 (except I think the #ifdef
PyObjC_HAVE_PYTHON_BOOL test should be removed, as it does the opposite
of what I thought it would: PyObjC_HAVE_PYTHON_BOOL is defined when
Python does _not_ have builtin bool support...).

Thought about this a bit more: this is not going to work in a useful way
in Python 2.2.

Just

Re: [Pyobjc-dev] shouldSelectRow not working as expected

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

On Friday, Feb 28, 2003, at 12:51 Europe/Amsterdam, Just van Rossum 
wrote:

> Just van Rossum wrote:
>
>> Here's a thought: what if the bridge would convert the False bool
>> instance to nil? Hm, this would only work with Python 2.3 unless we
>> add proper bool support to 2.2 ourselves (btw. plistlib.py contains
>> code that does just that, but only for that module).
>
> I just tried, and this indeed works for 2.3 (except I think the #ifdef
> PyObjC_HAVE_PYTHON_BOOL test should be removed, as it does the opposite
> of what I thought it would: PyObjC_HAVE_PYTHON_BOOL is defined when
> Python does _not_ have builtin bool support...).

Oops. I should have paid more attention... PyObjC_HAVE_PYTHON_BOOL 
should be defined only when python does have builtin bool support.

Ronald

Re: [Pyobjc-dev] shouldSelectRow not working as expected

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

On Friday, Feb 28, 2003, at 12:17 Europe/Amsterdam, Just van Rossum 
wrote:

> Ronald Oussoren wrote:
>
>> Right. Does the patch I just checked in solve the problem?
>
> Partly, it seems. However, you _must_ return an int/bool for methods
> that are declared to return a BOOL; when I return None instead I get an
> exception. I assume that's because ObjC can't see the difference 
> between
> a BOOL and a char at the time the conversion happens.

Right. As far as the runtime, and therefore the bridge, is concerned 
BOOL is an alias for 'unsigned char'.

>
> In my PythonBrowser playground I have an inconsitency, though. Two
> methods are supposed to return BOOLs, yet one is part of the
> NSOutlineViewDataSource protocol, the other is an NSOutlineView 
> delegate
> method (is there even a NSOutlineViewDelegate protocol?).

Not yet :-)

>
> class PythonBrowserModel(AutoBaseClass, NSOutlineViewDataSource):
>
>     [..snippo..]
>
>     def outlineView_isItemExpandable_(self, view, item):
>         # part of the NSOutlineViewDataSource protocol,
>         # must return int/bool
>         if item is None:
>             item = self.root
>         return item.isExpandable()
>
>     def outlineView_shouldEditTableColumn_item_(self, view, col, item):
>         # this is a delegate method of NSOutlineView, I _must_ return
>         # None as "NO", any other object as "YES", hence the "or None"
>         # hack.
>         return item.isEditable() or None
>
> I suppose this is not solvable without adding an NSOutlineViewDelegate
> informal protocol?

Yup. Feel free to add this to Lib/AppKit/__init__.py ;-). It should 
contain all the methods a NSOutlineView delegate can implement.

We should probably add informal_protocol definitions for all delegates 
in Cocoa.

>
> Here's a thought: what if the bridge would convert the False bool
> instance to nil? Hm, this would only work with Python 2.3 unless we add
> proper bool support to 2.2 ourselves (btw. plistlib.py contains code
> that does just that, but only for that module).

That would work only by accident. If the bit-pattern of the pointer to 
the (proxy-)object for a true value happened to contain 8 0-bits at the 
right location it would also be interpreted as NO by the objective-C 
side of thinks.

Not that adding a private bool type on Python 2.2 would be bad, it 
would allow for the creation of the right kind of NSNumber for boolean 
values, NSNumbers created using numberWithBool: have a different kind 
of representation in plist files. BTW. Later 2.2 versions introduce 
builtins for True and False, does that also introduce a bool type or 
are these just names for 1 and 0?

Ronald

[Pyobjc-dev] informal_protocol

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

On Friday, Feb 28, 2003, at 07:54 US/Eastern, Ronald Oussoren wrote:
> Yup. Feel free to add this to Lib/AppKit/__init__.py ;-). It should 
> contain all the methods a NSOutlineView delegate can implement.
>
> We should probably add informal_protocol definitions for all delegates 
> in Cocoa.

Yes.   When defining such a thing, there is no need to wrap methods 
where all of the arguments are objects and the return value is an 
object.

Correct?

I'm adding NSOutlineViewDelegate now.

b.bum

Re: [Pyobjc-dev] shouldSelectRow not working as expected

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

its working as expected now.

thanks, everyone.

--bob