Re: [flexcoders] function binding toString !! Additional information
1st; when i use function biding (textInput
text={myInstance.toString()}/) , function binding works fine
are you sure about that? I could be wrong, but I would guess that if
you add a button under the TextInput tag your TextInput text value
will not update as expected on the button click.
mx:Button label=Test click=myInstance.someProperty = 'testing'; /
(If in fact it does update for you, I would love to see your example
code since it's possible there is an aspect of binding that I am
missing.)
HOWEVER, the problem you are having with the item renderer is
somewhat related, but different, problem. Item renderers use 'data'
as generic object to hold the data passed to the item render. That
object itself is bindable AND if the entire data object changes the
functions and properties will update. However, changes to the
underlying properties or functions will not be detected without
setting up binding a little more explicitly. (Usually you don't get
compiler warnings, but it you run in debug mode you should get run
time messages in the console) My solution to this is to explicitly
bind the data property to an internal property of the item renderer
using MXML. When I do this the binding works correctly.
In my item renderer...
mx:Script
![CDATA[
[Bindable]
private var myInternalData:MyCustomClass;
]]
/mx:Script
mx:Binding source=(data as MyCustomClass) source=myInternalData /
mx:Label text={myInternalData.myFunction()} /
Hopefully that helps your item renderer problem.
You are correct. Functions can be bound BUT I think what Frederico
was pointing out is that there are some important things to
understand when binding with functions (which are stated in the
document that you referenced.) It is not as easy as just putting the
function in curly braces.
You can use ActionScript functions as the source of data binding
expressions when using a bindable property as an argument of the
function.
If you do not pass a parameter to the function then flex has no way
of knowing when to update the function. You can do a quick test of
this by running this test:
?xml version=1.0 encoding=utf-8?
mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
layout=vertical horizontalAlign=center
mx:Script
![CDATA[
[Bindable]
public var myData:String = 'old data';
private function myFunction(data:String = null):String{
return myData;
}
]]
/mx:Script
mx:Label text={myData} /
mx:Label text={myFunction(myData)} /
mx:Label text={myFunction()} /
mx:Button label=Test click=myData = 'new data'; /
/mx:Application
as you can see the first two labels will update correctly because
they have a reference to some underlying data. When that data
changes Flex knows to execute the function again. The other option
(as you pasted in your last email) is to dispatch an event from a
setter so that flex will know to update the function that relies on
the set data:
?xml version=1.0 encoding=utf-8?
mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
layout=vertical horizontalAlign=center
mx:Script
![CDATA[
private var _myData:String = 'old data';
public function set myData(value:String):void{
_myData = value;
dispatchEvent(new Event(myDataChanged));
}
[Bindable]
public function get myData():String{
return _myData;
}
[Bindable(event=myDataChanged)]
private function myFunction(data:String = null):String{
return _myData;
}
]]
/mx:Script
mx:Label text={myData} /
mx:Label text={myFunction(myData)} /
mx:Label text={myFunction()} /
mx:Button label=Test click=myData = 'new data'; /
/mx:Application
As you can see all the labels now update properly.
- Kevin
Re: [flexcoders] function binding toString !! Additional information
Kevin escreveu:
1st; when i use function biding (textInput
text={myInstance.toString()}/) , function binding works fine
are you sure about that? I could be wrong, but I would guess that if
you add a button under the TextInput tag your TextInput text value
will not update as expected on the button click.
mx:Button label=Test click=myInstance.someProperty = 'testing'; /
(If in fact it does update for you, I would love to see your example
code since it's possible there is an aspect of binding that I am missing.)
HOWEVER, the problem you are having with the item renderer is somewhat
related, but different, problem. Item renderers use 'data' as
generic object to hold the data passed to the item render. That
object itself is bindable AND if the entire data object changes the
functions and properties will update. However, changes to the
underlying properties or functions will not be detected without
setting up binding a little more explicitly. (Usually you don't get
compiler warnings, but it you run in debug mode you should get run
time messages in the console) My solution to this is to explicitly
bind the data property to an internal property of the item renderer
using MXML. When I do this the binding works correctly.
In my item renderer...
mx:Script
![CDATA[
[Bindable]
private var myInternalData:MyCustomClass;
]]
/mx:Script
mx:Binding source=(data as MyCustomClass) source=myInternalData /
mx:Label text={myInternalData.myFunction()} /
Hopefully that helps your item renderer problem.
You are correct. Functions can be bound BUT I think what Frederico
was pointing out is that there are some important things to understand
when binding with functions (which are stated in the document that you
referenced.) It is not as easy as just putting the function in curly
braces.
You can use ActionScript functions as the source of data binding
expressions *when using a bindable property** as an argument* of the
function.
If you do not pass a parameter to the function then flex has no way of
knowing when to update the function. You can do a quick test of this
by running this test:
?xml version=1.0 encoding=utf-8?
mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
layout=vertical horizontalAlign=center
mx:Script
![CDATA[
[Bindable]
public var myData:String = 'old data';
private function myFunction(data:String = null):String{
return myData;
}
]]
/mx:Script
mx:Label text={myData} /
mx:Label text={myFunction(myData)} /
mx:Label text={myFunction()} /
mx:Button label=Test click=myData = 'new data'; /
/mx:Application
as you can see the first two labels will update correctly because they
have a reference to some underlying data. When that data changes Flex
knows to execute the function again. The other option (as you pasted
in your last email) is to dispatch an event from a setter so that flex
will know to update the function that relies on the set data:
?xml version=1.0 encoding=utf-8?
mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
layout=vertical horizontalAlign=center
mx:Script
![CDATA[
private var _myData:String = 'old data';
public function set myData(value:String):void{
_myData = value;
dispatchEvent(new Event(myDataChanged));
}
[Bindable]
public function get myData():String{
return _myData;
}
[Bindable(event=myDataChanged)]
private function myFunction(data:String = null):String{
return _myData;
}
]]
/mx:Script
mx:Label text={myData} /
mx:Label text={myFunction(myData)} /
mx:Label text={myFunction()} /
mx:Button label=Test click=myData = 'new data'; /
/mx:Application
As you can see all the labels now update properly.
- Kevin
__ NOD32 2755 (20071229) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com
Thanks Kevin,
Great post on function binding.
I believe function binding is quite cool, BUT troublesome and needless.
Binding a property to a function with no parameters is the same as
binding to a getter. Most Binding issues can be solved using the
solution I first provided.
Regards,
Frederico Garcia
Re: [flexcoders] function binding toString !! Additional information
http://127.0.0.1:49661/help/index.jsp?topic=/com.adobe.flexbuilder.help/html/databinding_4.html
here; in the first example, there is a bindable function and it is not a
setter or getter.
so functions other then setters and getters can be binded!
so my question should have an answer...
by the way, i'm dont have to use function biding, i can make thinks work
without it, but when i saw it
i decided to use, cuz it is cool :) , and good in terms of code
readiblity...
so , check out te following example, an event triggers the binding of
the function and the function(is Enabled) is neither a getter
or a setter:
?xml version=1.0?
!-- binding/ASFunction.mxml --
mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
mx:Script
![CDATA[
import flash.events.Event;
// Define a function that gets invoked
// in response to the myFlagChanged event.
[Bindable(event=myFlagChanged)]
private function isEnabled():String {
if (myFlag)
return 'true';
else
return 'false';
}
private var _myFlag:Boolean = false;
// Define a setter method that dispatches the
// myFlagChanged event to trigger the data binding.
public function set myFlag(value:Boolean):void {
_myFlag = value;
dispatchEvent(new Event(myFlagChanged));
}
public function get myFlag():Boolean {
return _myFlag;
}
]]
/mx:Script
!-- Use the function as the source of a data binding expression. --
mx:TextArea id=myTA text={isEnabled()}/
!-- Modify the property, causing the setter method to
dispatch the myFlagChanged event to trigger data binding. --
mx:Button label=Clear MyFlag click=myFlag=false;/
mx:Button label=Set MyFlag click=myFlag=true;/
/mx:Application
Frederico Garcia wrote On 12/27/2007 02:57 PM:
yigit escreveu:
i think i'm misunderstood; because your solution suggestions does not
fit my problem.
first of all, functions can be binded. (with an event driven
architecture that triggers
the function to be executed and all bindable references be updated)
to see how it is done, take a look at the article in flex api :
http://127.0.0.1:64744/help/index.jsp?topic=/com.adobe.flexbuilder.help/html/databinding_4.html
http://127.0.0.1:64744/help/index.jsp?topic=/com.adobe.flexbuilder.help/html/databinding_4.html
(or search for [Bindable] function then click the second result)
after this quick information, i want to refigure my problem.
assume: myInstance:MyClass; //MyClass implements a bindable toString
method
my problem has two parts:
1st; when i use function biding (textInput
text={myInstance.toString()}/) , function binding works fine
except the itemRenderer (textInput text={data.toString()}/)
why? what is the problem? can't the VM detect the binding mechanism?
(by the way there isn't any compile time
warnings about the binding will not be able to run properly)
2nd: if i do not write toString (textInput text={myINstance}/),
although it calls toString method to find the
text value, function binding does never work (neither in itemRenderers
nor normal usage).
why? why cant the compiler detect the binding?
thnks in advance.
Frederico Garcia wrote On 12/26/2007 05:38 PM:
Jhonny Everson escreveu:
I guess that your solution has a problem, the circular reference to
toString.
it could be something like:
[Bindable] public var stringValue:String = ;
public function toString():String {
... ( some processing that results in a string var 'string1')
stringValue= string1;
return stringValue;
}
On 12/26/07, * Frederico Garcia* [EMAIL PROTECTED]
mailto:fmotagarcia%40kemelyon.com
mailto:fmotagarcia%40kemelyon.com
mailto:[EMAIL PROTECTED] mailto:fmotagarcia%40kemelyon.com
mailto:fmotagarcia%40kemelyon.com wrote:
yigit escreveu:
hi all;
i have a custom class which has a toString method; so i can
directly use
it as a source to textInput's text field.
i want to make binding work, i mean when the result of the toString
changes, i want the view to update itself automatically.
nameID field of roleRef is an instance of my class that implements
toString with function biding.
when i use this way:
mx:Label id=lbl text={roleRef.nameID}/
function binding on toString does not work
when i use this way:
mx:Label id=lbl text={roleRef.nameID.toString()}/
function biding on toString works, but inside an item renderer,
it does
not work.
mx:Label id=lbl text={data.nameID.toString()}/
is this a compiler bug or is this the normal behavior?
--
Flexcoders Mailing List
FAQ:
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Re: [flexcoders] function binding toString !! Additional information
override the set data function in your item renderer and bind your function
getter to an event you dispatch in there.
On Dec 27, 2007 2:39 AM, yigit [EMAIL PROTECTED] wrote:
i think i'm misunderstood; because your solution suggestions does not
fit my problem.
first of all, functions can be binded. (with an event driven architecture
that triggers
the function to be executed and all bindable references be updated)
to see how it is done, take a look at the article in flex api :
http://127.0.0.1:64744/help/index.jsp?topic=/com.adobe.flexbuilder.help/html/databinding_4.html
(or search for [Bindable] function then click the second result)
after this quick information, i want to refigure my problem.
assume: myInstance:MyClass; //MyClass implements a bindable toString
method
my problem has two parts:
1st; when i use function biding (textInput text={myInstance.toString()}/)
, function binding works fine
except the itemRenderer (textInput text={data.toString()}/)
why? what is the problem? can't the VM detect the binding mechanism? (by
the way there isn't any compile time
warnings about the binding will not be able to run properly)
2nd: if i do not write toString (textInput text={myINstance}/),
although it calls toString method to find the
text value, function binding does never work (neither in itemRenderers nor
normal usage).
why? why cant the compiler detect the binding?
thnks in advance.
Frederico Garcia wrote On 12/26/2007 05:38 PM:
Jhonny Everson escreveu:
I guess that your solution has a problem, the circular reference to
toString.
it could be something like:
[Bindable] public var stringValue:String = ;
public function toString():String {
... ( some processing that results in a string var 'string1')
stringValue= string1;
return stringValue;
}
On 12/26/07, * Frederico Garcia* [EMAIL
PROTECTED]fmotagarcia%40kemelyon.com
mailto:[EMAIL PROTECTED] fmotagarcia%40kemelyon.com wrote:
yigit escreveu:
hi all;
i have a custom class which has a toString method; so i can
directly use
it as a source to textInput's text field.
i want to make binding work, i mean when the result of the toString
changes, i want the view to update itself automatically.
nameID field of roleRef is an instance of my class that implements
toString with function biding.
when i use this way:
mx:Label id=lbl text={roleRef.nameID}/
function binding on toString does not work
when i use this way:
mx:Label id=lbl text={roleRef.nameID.toString()}/
function biding on toString works, but inside an item renderer,
it does
not work.
mx:Label id=lbl text={data.nameID.toString()}/
is this a compiler bug or is this the normal behavior?
--
Flexcoders Mailing List
FAQ:
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Search Archives:
http://www.mail-archive.com/flexcoders%40yahoogroups.com
Yahoo! Groups Links
__ NOD32 2747 (20071225) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com
I believe you can only bind vars and setters. By binding a function i
think it will only execute the function once. An easy workaround
is to
have a var containg the result of the toString function and bind the
property to that var. Something like:
[Bindable] public var stringValue:String = ;
public function toString():String {
stringValue= this.toString();
return stringValue;
}
mx:Label id=lbl text={data.nameID.stringValue}/
Regards
Frederico Garcia
--
Jhonny Everson
__ NOD32 2747 (20071225) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com
Yes, indeed there was a circular reference to toString. Thanks for the
correction. The general concept is the same though, and I think it's the
best way to solve the bind to function problem.
Regards
Frederico Garcia
--
j:pn
\\no comment
Re: [flexcoders] function binding toString !! Additional information
yigit escreveu:
i think i'm misunderstood; because your solution suggestions does not
fit my problem.
first of all, functions can be binded. (with an event driven
architecture that triggers
the function to be executed and all bindable references be updated)
to see how it is done, take a look at the article in flex api :
http://127.0.0.1:64744/help/index.jsp?topic=/com.adobe.flexbuilder.help/html/databinding_4.html
(or search for [Bindable] function then click the second result)
after this quick information, i want to refigure my problem.
assume: myInstance:MyClass; //MyClass implements a bindable toString
method
my problem has two parts:
1st; when i use function biding (textInput
text={myInstance.toString()}/) , function binding works fine
except the itemRenderer (textInput text={data.toString()}/)
why? what is the problem? can't the VM detect the binding mechanism?
(by the way there isn't any compile time
warnings about the binding will not be able to run properly)
2nd: if i do not write toString (textInput text={myINstance}/),
although it calls toString method to find the
text value, function binding does never work (neither in itemRenderers
nor normal usage).
why? why cant the compiler detect the binding?
thnks in advance.
Frederico Garcia wrote On 12/26/2007 05:38 PM:
Jhonny Everson escreveu:
I guess that your solution has a problem, the circular reference to
toString.
it could be something like:
[Bindable] public var stringValue:String = ;
public function toString():String {
... ( some processing that results in a string var 'string1')
stringValue= string1;
return stringValue;
}
On 12/26/07, * Frederico Garcia* [EMAIL PROTECTED]
mailto:fmotagarcia%40kemelyon.com
mailto:[EMAIL PROTECTED]
mailto:fmotagarcia%40kemelyon.com wrote:
yigit escreveu:
hi all;
i have a custom class which has a toString method; so i can
directly use
it as a source to textInput's text field.
i want to make binding work, i mean when the result of the toString
changes, i want the view to update itself automatically.
nameID field of roleRef is an instance of my class that implements
toString with function biding.
when i use this way:
mx:Label id=lbl text={roleRef.nameID}/
function binding on toString does not work
when i use this way:
mx:Label id=lbl text={roleRef.nameID.toString()}/
function biding on toString works, but inside an item renderer,
it does
not work.
mx:Label id=lbl text={data.nameID.toString()}/
is this a compiler bug or is this the normal behavior?
--
Flexcoders Mailing List
FAQ:
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Search Archives:
http://www.mail-archive.com/flexcoders%40yahoogroups.com
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Yahoo! Groups Links
__ NOD32 2747 (20071225) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com http://www.eset.com
I believe you can only bind vars and setters. By binding a function i
think it will only execute the function once. An easy workaround
is to
have a var containg the result of the toString function and bind the
property to that var. Something like:
[Bindable] public var stringValue:String = ;
public function toString():String {
stringValue= this.toString();
return stringValue;
}
mx:Label id=lbl text={data.nameID.stringValue}/
Regards
Frederico Garcia
--
Jhonny Everson
__ NOD32 2747 (20071225) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com http://www.eset.com
Yes, indeed there was a circular reference to toString. Thanks for the
correction. The general concept is the same though, and I think it's the
best way to solve the bind to function problem.
Regards
Frederico Garcia
__ NOD32 2747 (20071225) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com
Hi,
Functions are indeed bindable, but only special function are: getters
and setters. If you look carefully in the help topic you siggested the
example there is:
|* [Bindable(event=maxFontSizeChanged)]*| // Define public getter
method. |* public function get maxFontSize():Number {*| return
_maxFontSize; }
This, however is not what you want, since getters and setters work the
same way as vars, only they execute some code.
Using getters you could do something like:
[Bindable(event=changeEvent)]
public function get asString():String {
... ( some processing that results in a string var 'string1')
return string1;
}
every time you change the
Re: [flexcoders] function binding toString !! Additional information
i think i'm misunderstood; because your solution suggestions does not
fit my problem.
first of all, functions can be binded. (with an event driven
architecture that triggers
the function to be executed and all bindable references be updated)
to see how it is done, take a look at the article in flex api :
http://127.0.0.1:64744/help/index.jsp?topic=/com.adobe.flexbuilder.help/html/databinding_4.html
(or search for [Bindable] function then click the second result)
after this quick information, i want to refigure my problem.
assume: myInstance:MyClass; //MyClass implements a bindable toString method
my problem has two parts:
1st; when i use function biding (textInput
text={myInstance.toString()}/) , function binding works fine
except the itemRenderer (textInput text={data.toString()}/)
why? what is the problem? can't the VM detect the binding mechanism? (by
the way there isn't any compile time
warnings about the binding will not be able to run properly)
2nd: if i do not write toString (textInput text={myINstance}/),
although it calls toString method to find the
text value, function binding does never work (neither in itemRenderers
nor normal usage).
why? why cant the compiler detect the binding?
thnks in advance.
Frederico Garcia wrote On 12/26/2007 05:38 PM:
Jhonny Everson escreveu:
I guess that your solution has a problem, the circular reference to
toString.
it could be something like:
[Bindable] public var stringValue:String = ;
public function toString():String {
... ( some processing that results in a string var 'string1')
stringValue= string1;
return stringValue;
}
On 12/26/07, * Frederico Garcia* [EMAIL PROTECTED]
mailto:fmotagarcia%40kemelyon.com
mailto:[EMAIL PROTECTED]
mailto:fmotagarcia%40kemelyon.com wrote:
yigit escreveu:
hi all;
i have a custom class which has a toString method; so i can
directly use
it as a source to textInput's text field.
i want to make binding work, i mean when the result of the toString
changes, i want the view to update itself automatically.
nameID field of roleRef is an instance of my class that implements
toString with function biding.
when i use this way:
mx:Label id=lbl text={roleRef.nameID}/
function binding on toString does not work
when i use this way:
mx:Label id=lbl text={roleRef.nameID.toString()}/
function biding on toString works, but inside an item renderer,
it does
not work.
mx:Label id=lbl text={data.nameID.toString()}/
is this a compiler bug or is this the normal behavior?
--
Flexcoders Mailing List
FAQ:
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Search Archives:
http://www.mail-archive.com/flexcoders%40yahoogroups.com
http://www.mail-archive.com/flexcoders%40yahoogroups.com
Yahoo! Groups Links
__ NOD32 2747 (20071225) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com http://www.eset.com
I believe you can only bind vars and setters. By binding a function i
think it will only execute the function once. An easy workaround
is to
have a var containg the result of the toString function and bind the
property to that var. Something like:
[Bindable] public var stringValue:String = ;
public function toString():String {
stringValue= this.toString();
return stringValue;
}
mx:Label id=lbl text={data.nameID.stringValue}/
Regards
Frederico Garcia
--
Jhonny Everson
__ NOD32 2747 (20071225) Information __
This message was checked by NOD32 antivirus system.
http://www.eset.com http://www.eset.com
Yes, indeed there was a circular reference to toString. Thanks for the
correction. The general concept is the same though, and I think it's the
best way to solve the bind to function problem.
Regards
Frederico Garcia
