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From: James Kuyper <jameskuyper@verizon.net>
Newsgroups: comp.lang.c,comp.lang.java.programmer
Subject: Re: Self-updating relationship
Date: Thu, 3 Sep 2015 10:53:12 -0400
Organization: A noiseless patient Spider
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References: <relationship-20150902211808@ram.dialup.fu-berlin.de> <55E766BD.3060303@verizon.net> <spaces-20150902222406@ram.dialup.fu-berlin.de> <55E77D04.6080200@verizon.net> <properties-20150903001216@ram.dialup.fu-berlin.de> <55E78636.5000908@verizon.net> <ms8g5j$o5k$1@dont-email.me> <ms9llv$pto$1@dont-email.me>
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On 09/03/2015 10:32 AM, Jeff Higgins wrote:
> On 09/02/2015 11:52 PM, Jeff Higgins wrote:
>> On 09/02/2015 07:28 PM, James Kuyper wrote:
> 
>>> Your earlier version had:
>>>>      final javafx.beans.binding.NumberBinding spaces =
>>>>      height.subtract( number );
>>>
>>> which causes spaces.getValue() to behave like the equivalent of a C++
>>> member function whose return value is calculated using the specified
>>> formula freshly each time "spaces" is referred to. Is this a
>>> characteristic of binding.NumberBinding, or some more general Java
>>> feature?
>>
>> It's a characteristic of the
>> javafx.beans.binding.Binding<T> interface.
>> <https://docs.oracle.com/javase/8/javafx/api/javafx/beans/binding/Binding.html>
>>
> 
> Sorry, this is incorrect.
> It's a characteristic of the
> javafx.beans.property.Property<T> interface.
> <https://docs.oracle.com/javase/8/javafx/api/javafx/beans/property/Property.html>

According to Stefan Ram, using the following code:
>     final javafx.beans.binding.NumberBinding spaces =
>     height.subtract( number );

would cause the subtraction to be re-evaluated with the current values
of height and number, each time spaces.getValue() is called, while


>     final javafx.beans.property.IntegerProperty spaces
>     = new javafx.beans.property.SimpleIntegerProperty
>     ( height.getValue() - number.getValue() );

would cause the subtraction to be performed only once, when spaces is
created. Are you saying he got those reversed? Or something more
complicated than that?
-- 
James Kuyper