Hi Laurent,
(sorry for the longish post)
I did some simple tests where the bound variable is not actually bound to a
CoreData store, but to a method in the custom NSManagedObject class..
(btw - I am not sure if anyone else noticed but a difference between 0.4 and
0.5, is that when binding to custom methods now, the methods have to be
mentioned in the valueForUndefinedKey method of the NSManagedObject - before
they did not need to be - but maybe in 0.4, this was a lucky time dependency,
with the method being loaded before being queried by the view).
- Returning a (ruby) number like 45.3 will not be displayed in the column (with
and without formatter) or in fact a plain NSTextField (so it does not seem to
be a table cell issue) but returning
NSDecimalNumber.decimalNumberWithString("45.3") - will be displayed correctly
in both.
- Same issue when binding to a class with only NSObject as the super.
- I also did do some test with the core data stack and KVC/KVO, binding etc and
everything worked ok. I now think this issue has nothing to do with CoreData.
- My current suspicion is that the NSTextField is being sent a setObjectValue
message which works fine with NSDecimalNumbers - it does not work with MacRuby
Floats, or with NSNumbers - although i would expect it to since they are
objects.
(bolds added by me for comprehension)
irb(main):005:0> framework "Cocoa"
=> true
irb(main):006:0> tf = NSTextField.alloc.init
=> #<NSTextField:0x20026c560>
irb(main):007:0> num = NSNumber.numberWithFloat(23.3)
=> 23.2999992370605
irb(main):008:0> tf.setObjectValue(num)
=> #<NSTextField:0x20026c560>
irb(main):009:0> p tf.stringValue
"0"
=> "0"
irb(main):010:0> tf.setFloatValue(23.3)
=> #<NSTextField:0x20026c560>
irb(main):011:0> p tf.stringValue
"23.29999923706055"
=> "23.29999923706055"
I will add this to the MacRuby bugs a bit later.
re NSDecimalNumber -> leaving it "untouched" as you said, is, in my opinion
the right thing, it would be too confusing for it to have different behavior
than what is in the docs.
Cheers,
John
On Nov 27, 2009, at 9:22 PM, Laurent Sansonetti wrote:
> Hi John,
>
> This may be a bug in MacRuby, I don't know bindings well enough. It would be
> cool if you could reduce the problem into a small Ruby script.
>
> We are indeed unboxing NSNumbers automatically. NSDecimalNumber seems to be
> left untouched, which could explain why the normal arithmetic operators do
> not work.
>
> Laurent
>
> On Nov 27, 2009, at 7:50 AM, John Shea wrote:
>
>> Hi all,
>>
>> does any one know whether there is an issue with binding to floats, doubles
>> in core data with macruby?
>>
>> For example:
>>
>> 1 I firstly, create an attribute foo which is set as a double or a float in
>> the core data model
>> 2. i bind it to a table column
>> 3. I set foo to 300.3 in code (not through the user interface)
>> 4. it comes through as 1 (or 1.00 if formatted - which is probably neither
>> here nor there)
>>
>> If i do the same but set the attribute to be of type decimal - then the
>> number 300.3 comes through fine.
>>
>> The problem then is that is that the class of foo is NSDecimalNumber - and
>> its really painful doing calculations with NSDecimalNumbers given that
>> normal arithmetic operators do not work.
>> I haven't found it to be that accurate either (at least in Objective C) -
>> compared to ruby floats.
>>
>> The strange thing is that both end up (in macruby) inheriting from NSNumber
>> - but somehow the binding cannot make sense of it.
>>
>> Is it possible that there is a non macruby translation going on? - an
>> unboxing - because the binding/kvc access thinks that foo is a float? (which
>> it might be, in the persistent store - but does not seem to be by the time
>> its accessed).
>>
>> I can think of work arounds - but i thought i better check with the experts
>> first ;-).
>>
>> Cheers,
>> J
>>
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>
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