RE: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
Actually, preventDefault() does NOT prevent other listeners from executing; this is what stopPropagation() and stopImmediatePropagation() do. preventDefault() simply sets the flag returned by isDefaultPrevented() to be true. However, some event-dispatching code in the Player or the framework is written like this (and you can do the same thing in your apps): dispatchEvent(event); if (!event.isDefaultPrevented()) doSomethingByDefault(); So calling preventDefault() prevents doSomethingByDefault() from being executed. But doSomethingByDefault() is not a listener. - Gordon From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Danko Kozar Sent: Friday, March 09, 2007 1:52 AM To: flexcoders@yahoogroups.com Subject: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex? Jason, this was an eye-opener! Till now I didn't realize that an event listener can cancel another listeners. But the preventDefault() method of the Event class does exactly that. This is the way I should go with a PagableGrid. Thanks! --- In flexcoders@yahoogroups.com mailto:flexcoders%40yahoogroups.com , Jason Hawryluk [EMAIL PROTECTED] wrote: As a follow up to the last response, take note of the event.preventDefault(); in the handler for HEADER_RELEASE, and the fact that I don't do a refresh on the ListCollectionView after adding the sort to it. jason -Message d'origine- De : flexcoders@yahoogroups.com mailto:flexcoders%40yahoogroups.com [mailto:flexcoders@yahoogroups.com mailto:flexcoders%40yahoogroups.com ]De la part de Danko Kozar Envoyé : jeudi 8 mars 2007 11:48 À : flexcoders@yahoogroups.com mailto:flexcoders%40yahoogroups.com Objet : [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex? Private methods and variables drive me nuts.. For example, I'd like to make a simple DataGrid change: make headers clickable without refreshing the grid (just toggle a sort icon). (I need this behaviour because I'd like to have a paging DataGrid which only propagates the sort column/direction info to a record- feching routine on a server) So, I try to remove a collection.refresh(); line from the sortByColumn() function, but I can't - because it's private. Then, I try to make a new function called sortByColumn2 (that's a copy of the first one, but without refresh stuff) and alter the headerReleaseHandler which calls it, but I can't - cause it's private. And finally, I am trying to add the following code to the constructor (yes, the constructor is public, huh.. :-)) to neutralize the event listener: removeEventListener(DataGridEvent.HEADER_RELEASE, headerReleaseHandler, false, EventPriority.DEFAULT_HANDLER); ... but I can't cause headerReleaseHandler is private and can't be seen from a subclass! And then, I give up.. :-) My conclussion is that Flex framework classes are not extensible enough and I really can't see a reason. Copying the whole DataGrid class and it's renderer, style, etc. classes isn't a solution, we all agree. If not other reason - it's not the OOP way. So, I'm tempted to go to a C:\Program Files\Adobe\Flex Builder 2 \Flex SDK 2\frameworks\source\mx\ folder and make a global search and replace on all files in this folder. You guess... replace private with protected... :-) --- In flexcoders@yahoogroups.com mailto:flexcoders%40yahoogroups.com , Dana Gutride dgutride@ wrote: Recently on this list, somebody said that the Flex framework team has been surprised at the resistance many developers have to subclassing and they'd like to understand it better. I'd like to put my 2 cents into this discussion because maybe we can come up with some good answers. I think the ability to extend the existing framework is fabulous, but I find that I am hesitant to subclass or extend the existing classes. Recently, I spent several days trying to override the placeSortArrow function on the datagrid. I ended up ditching my code because there were so many private variables used by the existing placeSortArrow() function that I would need to rewrite most of the datagrid.as file. I've bought books and searched online for answers, but I haven't found anything satisfactory yet. Maybe if there were more resources (even if we had to pay for them), we would find more developers extending the flex framework. Dana
Re: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
On Thursday 08 Mar 2007, Danko Kozar wrote: Private methods and variables drive me nuts.. When I did Java, I always made my private variables 'protected', but the real Java guys tole me that was a bad idea for some reason. -- Tom Chiverton Helping to economically enhance user-centric customers On: http://thefalken.livejournal.com This email is sent for and on behalf of Halliwells LLP. Halliwells LLP is a limited liability partnership registered in England and Wales under registered number OC307980 whose registered office address is at St James's Court Brown Street Manchester M2 2JF. A list of members is available for inspection at the registered office. Any reference to a partner in relation to Halliwells LLP means a member of Halliwells LLP. Regulated by the Law Society. CONFIDENTIALITY This email is intended only for the use of the addressee named above and may be confidential or legally privileged. If you are not the addressee you must not read it and must not use any information contained in nor copy it nor inform any person other than Halliwells LLP or the addressee of its existence or contents. If you have received this email in error please delete it and notify Halliwells LLP IT Department on 0870 365 8008. For more information about Halliwells LLP visit www.halliwells.com. Yahoo! Groups Sponsor ~-- Something is new at Yahoo! Groups. Check out the enhanced email design. http://us.click.yahoo.com/kOt0.A/gOaOAA/yQLSAA/nhFolB/TM ~- -- Flexcoders Mailing List FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.com Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/flexcoders/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/flexcoders/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
Danko,
See below extended datagrid and sample application to do what you want. I
realize its frustrating when you need to do things only to find yourself
blocked in the obvious way; but there is definitely more then one way to
skin a cat (so to speak).
Im sure future versions of the flex framework will allow a more elegant
solutions for the day to day problems we are faced with. I too often find my
self perplexed at the reasoning to privatize certain functions and
properties; but more often then not, a work around can be found that does
not require one to rewrite the base components.
Frustration is part of the learning process. Things that seem obvious are
not always so.
Anyway, I hope the below code and sample set you on your way to
accomplishing your task.
cheers
jason
Here is the application code:
?xml version=1.0 encoding=utf-8?
mx:Application xmlns:mx=http://www.adobe.com/2006/mxml; layout=absolute
xmlns:com=com.*
com:DataGridEX sortableColumns=true id=DGItems x=10 y=10
width=666 height=246
mx:ArrayCollection
mx:Object ratethis=Item 1 value=2 ratethis2=Item 1
value2=1 value3=50/
mx:Object ratethis=Item 2 value=1 ratethis2=Item 2
value2=2 value3=120/
mx:Object ratethis=Item 3 value=3 ratethis2=Item 3
value2=3 value3=4/
mx:Object ratethis=Item 4 value=4 ratethis2=Item 4
value2=4 value3=5/
mx:Object ratethis=Item 5 value=2 ratethis2=Item 5
value2=5 value3=3/
mx:Object ratethis=Item 6 value=0 ratethis2=Item 6
value2=6 value3=0/
mx:Object ratethis=Item 7 value=3 ratethis2=Item 7
value2=7 value3=0/
mx:Object ratethis=Item 8 value=4 ratethis2=Item 8
value2=8 value3=4/
mx:Object ratethis=Item 9 value=5 ratethis2=Item 9 value2=9
value3=2/
mx:Object ratethis=Item 10 value=0 ratethis2=Item 10 value2=10
value3=3/
/mx:ArrayCollection
com:columns
mx:DataGridColumn id=col1 dataField=ratethis headerText=Rate
This/
mx:DataGridColumn id=col2 dataField=value
headerText=Rating /
mx:DataGridColumn id=col3 dataField=ratethis2
headerText=Rate This 2/
mx:DataGridColumn id=col4 dataField=value2
headerText=Rating 2 /
/com:columns
/com:DataGridEX
/mx:Application
Here is the extended grid (place in a folder called com)
package com
{
import mx.controls.DataGrid;
import mx.events.DataGridEvent;
import mx.collections.ListCollectionView;
import mx.controls.dataGridClasses.DataGridColumn;
import mx.collections.Sort;
import mx.collections.SortField;
public class DataGridEX extends DataGrid
{
private var collectioView:ListCollectionView;
public function DataGridEX()
{
super();
addEventListener(DataGridEvent.HEADER_RELEASE,handleSort);
}
private function handleSort(event:DataGridEvent):void{
//don't let the normal sort go through
event.preventDefault();
var sort:Sort = new Sort();
//get the column clicked
var currentCol:DataGridColumn = DataGridColumn(event.itemRenderer.data);
//reverse the current sort
currentCol.sortDescending = !currentCol.sortDescending;
//add the new sort to the collection so the grid can use it
//to update the header display
sort.fields = [new SortField(currentCol.dataField,
true,currentCol.sortDescending)];
collectioView.sort = sort;
//reset the colums array for our sort arrow display
//to take effect
columns = columns;
}
/**
* override the setting of the dataprovider so we can get a
* local listcollection set up
**/
override public function get dataProvider():Object
{
return super.dataProvider;
}
override public function set dataProvider(value:Object):void
{
super.dataProvider = value;
collectioView = ListCollectionView(value);
}
}
}
-Message d'origine-
De : flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] la
part de Danko Kozar
Envoyé : jeudi 8 mars 2007 11:48
À : flexcoders@yahoogroups.com
Objet : [flexcoders] Re: Are other developers hesitant to extend existing
classes in Flex?
Private methods and variables drive me nuts..
For example, I'd like to make a simple DataGrid change: make headers
clickable without refreshing the grid (just toggle a sort icon).
(I need this behaviour because I'd like to have a paging DataGrid
which only propagates the sort column/direction info to a record-
feching routine on a server)
So, I try to remove a collection.refresh(); line from
the sortByColumn() function, but I can't - because it's private.
Then, I try to make a new function called sortByColumn2 (that's a
copy of the first one, but without refresh stuff) and alter
the headerReleaseHandler which calls it, but I can't - cause it's
private.
And finally, I am trying to add the following code to the
constructor (yes, the constructor is public, huh.. :-))
to neutralize the event listener:
removeEventListener(DataGridEvent.HEADER_RELEASE,
headerReleaseHandler,
false
RE: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
As a follow up to the last response, take note of the event.preventDefault(); in the handler for HEADER_RELEASE, and the fact that I don't do a refresh on the ListCollectionView after adding the sort to it. jason -Message d'origine- De : flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] la part de Danko Kozar Envoyé : jeudi 8 mars 2007 11:48 À : flexcoders@yahoogroups.com Objet : [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex? Private methods and variables drive me nuts.. For example, I'd like to make a simple DataGrid change: make headers clickable without refreshing the grid (just toggle a sort icon). (I need this behaviour because I'd like to have a paging DataGrid which only propagates the sort column/direction info to a record- feching routine on a server) So, I try to remove a collection.refresh(); line from the sortByColumn() function, but I can't - because it's private. Then, I try to make a new function called sortByColumn2 (that's a copy of the first one, but without refresh stuff) and alter the headerReleaseHandler which calls it, but I can't - cause it's private. And finally, I am trying to add the following code to the constructor (yes, the constructor is public, huh.. :-)) to neutralize the event listener: removeEventListener(DataGridEvent.HEADER_RELEASE, headerReleaseHandler, false, EventPriority.DEFAULT_HANDLER); ... but I can't cause headerReleaseHandler is private and can't be seen from a subclass! And then, I give up.. :-) My conclussion is that Flex framework classes are not extensible enough and I really can't see a reason. Copying the whole DataGrid class and it's renderer, style, etc. classes isn't a solution, we all agree. If not other reason - it's not the OOP way. So, I'm tempted to go to a C:\Program Files\Adobe\Flex Builder 2 \Flex SDK 2\frameworks\source\mx\ folder and make a global search and replace on all files in this folder. You guess... replace private with protected... :-) --- In flexcoders@yahoogroups.com, Dana Gutride [EMAIL PROTECTED] wrote: Recently on this list, somebody said that the Flex framework team has been surprised at the resistance many developers have to subclassing and they'd like to understand it better. I'd like to put my 2 cents into this discussion because maybe we can come up with some good answers. I think the ability to extend the existing framework is fabulous, but I find that I am hesitant to subclass or extend the existing classes. Recently, I spent several days trying to override the placeSortArrow function on the datagrid. I ended up ditching my code because there were so many private variables used by the existing placeSortArrow() function that I would need to rewrite most of the datagrid.as file. I've bought books and searched online for answers, but I haven't found anything satisfactory yet. Maybe if there were more resources (even if we had to pay for them), we would find more developers extending the flex framework. Dana
Re: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
On Thursday 22 Feb 2007, Paul DeCoursey wrote: support our REST based Web Services. But also URLRequest is a final class and cannot be extended. So you extend the parent, and cut and paste most of the code. Final isn't the end of the world :-) -- Tom Chiverton Helping to continuously drive cross-platform models This email is sent for and on behalf of Halliwells LLP. Halliwells LLP is a limited liability partnership registered in England and Wales under registered number OC307980 whose registered office address is at St James's Court Brown Street Manchester M2 2JF. A list of members is available for inspection at the registered office. Any reference to a partner in relation to Halliwells LLP means a member of Halliwells LLP. Regulated by the Law Society. CONFIDENTIALITY This email is intended only for the use of the addressee named above and may be confidential or legally privileged. If you are not the addressee you must not read it and must not use any information contained in nor copy it nor inform any person other than Halliwells LLP or the addressee of its existence or contents. If you have received this email in error please delete it and notify Halliwells LLP IT Department on 0870 365 8008. For more information about Halliwells LLP visit www.halliwells.com. -- Flexcoders Mailing List FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.com Yahoo! Groups - Join or create groups, clubs, forums amp; communities. Links * To visit your group on the web, go to: http://groups.yahoo.com/group/flexcoders/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/flexcoders/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups - Join or create groups, clubs, forums amp; communities. is subject to: http://docs.yahoo.com/info/terms/
Re: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
Tom Chiverton wrote: On Thursday 22 Feb 2007, Paul DeCoursey wrote: support our REST based Web Services. But also URLRequest is a final class and cannot be extended. So you extend the parent, and cut and paste most of the code. Final isn't the end of the world :-) In this case it is since the source for URLRequest is not available, URLRequest is a flash class not a mx class. To make it work we would need to implement the entire HTTP client stack using sockets. Not a small undertaking. -- Flexcoders Mailing List FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.com Yahoo! Groups - Join or create groups, clubs, forums amp; communities. Links * To visit your group on the web, go to: http://groups.yahoo.com/group/flexcoders/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/flexcoders/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups - Join or create groups, clubs, forums amp; communities. is subject to: http://docs.yahoo.com/info/terms/
Re: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
you need access to a handful of private variables and functions in the parent class I have extended quite some components aswell. What i found out however, was that in the en i most of the time did not need those private variables and methods. At the end of a day full of fiddling i found a variable or method within the mx_internal namspace (which is publicly available). So now when i need to extend something i make sure i check all definitions of mx_internal first. Greetz Erik
Re: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
On Thursday 22 Feb 2007, Paul J DeCoursey wrote: In this case it is since the source for URLRequest is not available, URLRequest is a flash class not a mx class. To make it work we would need to implement the entire HTTP client stack using sockets. Not a small undertaking. *ahh* :-) -- Tom Chiverton Helping to heterogeneously customize vertical networks This email is sent for and on behalf of Halliwells LLP. Halliwells LLP is a limited liability partnership registered in England and Wales under registered number OC307980 whose registered office address is at St James's Court Brown Street Manchester M2 2JF. A list of members is available for inspection at the registered office. Any reference to a partner in relation to Halliwells LLP means a member of Halliwells LLP. Regulated by the Law Society. CONFIDENTIALITY This email is intended only for the use of the addressee named above and may be confidential or legally privileged. If you are not the addressee you must not read it and must not use any information contained in nor copy it nor inform any person other than Halliwells LLP or the addressee of its existence or contents. If you have received this email in error please delete it and notify Halliwells LLP IT Department on 0870 365 8008. For more information about Halliwells LLP visit www.halliwells.com. Yahoo! Groups Sponsor ~-- Check out the new improvements in Yahoo! Groups email. http://us.click.yahoo.com/4It09A/fOaOAA/yQLSAA/nhFolB/TM ~- -- Flexcoders Mailing List FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.com Yahoo! Groups - Join or create groups, clubs, forums amp; communities. Links * To visit your group on the web, go to: http://groups.yahoo.com/group/flexcoders/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/flexcoders/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups - Join or create groups, clubs, forums amp; communities. is subject to: http://docs.yahoo.com/info/terms/
Re: [flexcoders] Re: Are other developers hesitant to extend existing classes in Flex?
If you want to say that we shouldn't rely on needing access to any private variables, it's only a small difference to say it's OK to rely on mx_internal variables. The internal vars are marked as such because they might change in future releases. So if the objection is that your code might break because Adobe releases updates to the framework class you're using, then the same problem exists if you use the mx_internal vars. And I agree, Adobe made design choices about what you should need access to when you are extending components. This means they run into some of the same coding problems if they were to try to subclass these classes as well. But all that means is that Adobe can't make the extensions that we also can't make. And let's remember that the choices made by the Adobe flex framework team are just choices made by other programmers (albeit some damn good ones), but fallible programmers nonetheless. They try to anticipate what will be needed to make powerful extensions of components. But it's hard to look down the road and figure out what people will want to do. And often there is a workaround that can accomplish what you need without accessing private vars or methods. I've gone this route as well many times. But I think that it's not accurate to say that there is always a solution like this. And even if you can get it to work, sometimes you end up with such a convoluted solution, and you have to do much more processing work (removing child components that were added, intercepting events dispatched and stopping or redispatching...) which opens the door to more bugs. So obviously it's a double-edged sword to ever copy-paste framework classes. I guess it's just my personal opinion that it can be well worth it. Doug On 2/22/07, EECOLOR [EMAIL PROTECTED] wrote: you need access to a handful of private variables and functions in the parent class I have extended quite some components aswell. What i found out however, was that in the en i most of the time did not need those private variables and methods. At the end of a day full of fiddling i found a variable or method within the mx_internal namspace (which is publicly available). So now when i need to extend something i make sure i check all definitions of mx_internal first. Greetz Erik
