Home » Modeling » EMF » Question about ItemPropertyDescriptor#getId(Object)
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| Re: Question about ItemPropertyDescriptor#getId(Object) [message #417918 is a reply to message #417915] |
Fri, 28 March 2008 17:21   |
 Stefan Baramov
Messages: 33
Registered: July 2009 |
Member |
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Ed,
Point taken, I do not use the parentReferences array so the simple
solution was okay. However, you are correct the feature could be null.
Unfortunately I do not have a clear understanding on how and for what
the patternReferences are used. So excuse my lame solution but here it is :
public String getId(Object object) {
if (feature != null) {
return feature.getName();
} else if (parentReferences != null && parentReferences.length > 0){
// concatenate all names with dot as a separator.
final StringBuilder compositeId = new StringBuilder();
for (int i = 0; i < parentReferences.length; ++i) {
if (i != 0) {
compositeId.append(".");
}
compositeId.append(parentReferences[i].getName());
}
return compositeId.toString();
} else {
return Integer.toHexString(hashCode());
}
}
the #2 case is the first that come to mind, as I have said, I do not
understand the use case for the patternReferences. For one, the
ItemProviderAdapter is not using it so it is safe for me to assume that
this is not use at all at least in my case.
The #3 case should never happen if the javadoc is correct. The case
where the feature == null and patternReferences is an empty array should
be an invalid state. If this is the case then may be throwing
IllegalStateException is more appropriate.
FYI: My case is quite simple. I have a graphic editor for a specialized
XML file. The editor utilizes the TabbedPropertySheetPage provided by
the platform. The tabs are PropertySection's and contains fields to
render particular properties. These property sections utilize the
corresponding property descriptors to read and write the property value.
The property descriptor is looked up by its ID. Hence the ID is vital
for me.
At the end, in my humble opinion, the getId() method needs a better
implementation.
Thanks,
Stefan
Ed Merks wrote:
> Stefan,
>
> There isn't necessarily always a feature (there's also the
> parentReferences array). So we don't have anything else that's unique.
> ItemPropertyDescriptor does have a getFeature method, but I'm not sure
> what exactly your use case is... Of course you could use
> XyzEditPlugin.INSTANCE.get("_UI_<EClass-Name>_<EStructuralFeature_Name >_feature")
> to get the translated string; the key itself would have been a better ID...
>
>
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| Re: Question about ItemPropertyDescriptor#getId(Object) [message #417921 is a reply to message #417918] |
Fri, 28 March 2008 17:54 |
Ed Merks
Messages: 33141
Registered: July 2009 |
Senior Member |
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Stefan,
Comments below.
Stefan Baramov wrote:
> Ed,
> Point taken, I do not use the parentReferences array so the simple
> solution was okay. However, you are correct the feature could be null.
> Unfortunately I do not have a clear understanding on how and for what
> the patternReferences are used.
They're not much used!
> So excuse my lame solution but here it is :
>
> public String getId(Object object) {
> if (feature != null) {
> return feature.getName();
>
> } else if (parentReferences != null && parentReferences.length > 0){
> // concatenate all names with dot as a separator.
> final StringBuilder compositeId = new StringBuilder();
> for (int i = 0; i < parentReferences.length; ++i) {
> if (i != 0) {
> compositeId.append(".");
> }
> compositeId.append(parentReferences[i].getName());
> }
>
> return compositeId.toString();
>
> } else {
> return Integer.toHexString(hashCode());
> }
> }
Given that something like hash code is completely arbitrary, I'm not
sure how it could ever be used for lookup unless you used this method to
find the ID in the first place.
>
> the #2 case is the first that come to mind, as I have said, I do not
> understand the use case for the patternReferences. For one, the
> ItemProviderAdapter is not using it so it is safe for me to assume
> that this is not use at all at least in my case.
>
> The #3 case should never happen if the javadoc is correct. The case
> where the feature == null and patternReferences is an empty array
> should be an invalid state. If this is the case then may be throwing
> IllegalStateException is more appropriate.
True, but folks could override these things to do all manner of things I
might not anticipate.
>
>
> FYI: My case is quite simple. I have a graphic editor for a
> specialized XML file. The editor utilizes the TabbedPropertySheetPage
> provided by the platform. The tabs are PropertySection's and contains
> fields to render particular properties. These property sections
> utilize the corresponding property descriptors to read and write the
> property value. The property descriptor is looked up by its ID. Hence
> the ID is vital for me.
>
> At the end, in my humble opinion, the getId() method needs a better
> implementation.
I think I need to understand the use case better. I know that many
people uses the properties view include the tabbed property sheet page,
yet no one has been concerned about looking up a property by ID. The ID
is mostly just used internal to the property sheet implementations.
Given that it's been working in this kind of crummy way for a long time,
I can't be sure that folks aren't relying on the current behavior. So
while not ideal, you definitely can get the string used as the ID by
fetching it from the plugin...
>
> Thanks,
> Stefan
>
> Ed Merks wrote:
>> Stefan,
>>
>> There isn't necessarily always a feature (there's also the
>> parentReferences array). So we don't have anything else that's
>> unique. ItemPropertyDescriptor does have a getFeature method, but
>> I'm not sure what exactly your use case is... Of course you could
>> use
>> XyzEditPlugin.INSTANCE.get("_UI_<EClass-Name>_<EStructuralFeature_Name >_feature")
>> to get the translated string; the key itself would have been a better
>> ID...
>>
>>
Ed Merks
Professional Support: https://www.macromodeling.com/
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| Re: Question about ItemPropertyDescriptor#getId(Object) [message #417925 is a reply to message #417924] |
Fri, 28 March 2008 19:52 |
Ed Merks
Messages: 33141
Registered: July 2009 |
Senior Member |
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Stefan,
I agree it doesn't seem ideal, but I'm also not inclined to change
something when the change is just as likely to break existing users as
it is to make someone else happy. Since your the first to ever complain
about it, I'm not so sure. But if others complain in the future, I'll
remember. In general, I think the IItemPropertySource and IItem
PropertyDescriptor APIs are more flexible; i.e., the later would allow
you to find the matching feature with the feature object itself...
Stefan Baramov wrote:
> >>
> >> At the end, in my humble opinion, the getId() method needs a better
> >> implementation.
> > I think I need to understand the use case better. I know that many
> > people uses the properties view include the tabbed property sheet page,
> > yet no one has been concerned about looking up a property by ID.
> The ID
> > is mostly just used internal to the property sheet implementations.
> > Given that it's been working in this kind of crummy way for a long
> time,
> > I can't be sure that folks aren't relying on the current behavior. So
> > while not ideal, you definitely can get the string used as the ID by
> > fetching it from the plugin...
>
> It is quite surprising to me that no one has reported this problem
> before. Essentially I am using the
> org.eclipse.emf.edit.ui.provider.PropertySource class to read and
> write properties value. Therefore I need a reliable property ID.
>
> Anyway, I have solved my problem by overriding the ItemProviderAdapter
> and ItemProviderDescriptor to have a better ID. However, I still
> believe that this should be filed as a bug and fixed in a future
> version. Of course in the case where I am the only one with that
> believe then never mind me.
>
> Thanks
> Stefan
Ed Merks
Professional Support: https://www.macromodeling.com/
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| Re: Question about ItemPropertyDescriptor#getId(Object) [message #417953 is a reply to message #417924] |
Mon, 31 March 2008 12:59 |
Sébastien Gandon
Messages: 184
Registered: July 2009 |
Senior Member |
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I too had the same problem and found the same solution.
My use case was to build a generic text editor to include in a Form using
databinding (see the class below).
The class is instanciated with a IItemPropertyDescriptor in order to get
the label and the feature.
in order to get the IItemPropertyDescriptor of one of my model feature I
use the folowing which uses the feature name as the ID:
IItemPropertyDescriptor propertyDescriptor =
**AdapterFactoryItemDelegator**.getPropertyDescriptor(Middle waresFactory.eINSTANCE.createMiddleware(),
MiddlewaresPackage.Literals.MIDDLEWARE__NAME.getName());
here is the class :
public class EmfFormTextRow {
// Required to allow space for field decorations
public static final int CONTROL_HORIZONTAL_INDENT = 3;
private EditingDomain editingDomain;
private ISWTObservableValue textObservable;
private Binding textBinding;
private DataBindingContext bindingContext;
private IItemPropertyDescriptor propertyDesc;
/**
* create the adapter class to the EMF feature
*/
public EmfFormTextRow(EditingDomain editingDomain,
IItemPropertyDescriptor propertyDescriptor, DataBindingContext
bindingContext) {
this.editingDomain = editingDomain;
this.propertyDesc = propertyDescriptor;
this.bindingContext = bindingContext;
}
public void createContents(Composite parent, FormToolkit toolkit, int
span) {
createLabel(parent, toolkit);
Text text = toolkit.createText(parent, "", SWT.SINGLE); //$NON-NLS-1$
text.setLayoutData(createGridData(span));
textObservable = SWTObservables.observeText(text, SWT.Modify);
}
/**
* @param parent
* @param toolkit
*/
private void createLabel(Composite parent, FormToolkit toolkit) {
Label label = toolkit.createLabel(parent,
propertyDesc.getDisplayName(null), SWT.NONE);
// Label label = toolkit.createLabel(parent, feature.getName(), SWT.NONE);
label.setForeground(toolkit.getColors().getColor(IFormColors .TITLE));
}
protected GridData createGridData(int span) {
GridData gd = new GridData(span == 2 ? GridData.FILL_HORIZONTAL :
GridData.HORIZONTAL_ALIGN_FILL);
gd.widthHint = 20;
gd.horizontalSpan = span - 1;
gd.horizontalIndent = CONTROL_HORIZONTAL_INDENT;
return gd;
}
public void modelChanged(EObject emfObject) {
if (textBinding != null) {
textBinding.dispose();
}
IObservableValue source = EMFEditObservables.observeValue(editingDomain,
emfObject, (EStructuralFeature) propertyDesc.getFeature(emfObject));
textBinding = bindingContext.bindValue(textObservable, source, new
UpdateValueStrategy(UpdateValueStrategy.POLICY_UPDATE), new
UpdateValueStrategy(UpdateValueStrategy.POLICY_UPDATE));
}
/**
* remove the binding between text control and the emf object
*/
public void dispose() {
if (textBinding != null) {
textBinding.dispose();
}
}
/**
* set the focus to the text control
*/
public void setFocus() {
if (textObservable != null) {
((Text) textObservable.getWidget()).setFocus();
}
}
}
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| Re: Question about ItemPropertyDescriptor#getId(Object) [message #417954 is a reply to message #417953] |
Mon, 31 March 2008 13:20 |
Ed Merks
Messages: 33141
Registered: July 2009 |
Senior Member |
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|
This is a multi-part message in MIME format.
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Comments below.
SeB.fr wrote:
> I too had the same problem and found the same solution.
> My use case was to build a generic text editor to include in a Form
> using databinding (see the class below).
>
> The class is instanciated with a IItemPropertyDescriptor in order to
> get the label and the feature.
> in order to get the IItemPropertyDescriptor of one of my model feature
> I use the folowing which uses the feature name as the ID:
> IItemPropertyDescriptor propertyDescriptor =
> **AdapterFactoryItemDelegator**.getPropertyDescriptor(Middle waresFactory.eINSTANCE.createMiddleware(),
> MiddlewaresPackage.Literals.MIDDLEWARE__NAME.getName());
IItemPropertyDescriptor has a getFeature method so you could match by
feature. It's annoying that we mistakenly made the ID be a string.
:-( Perhaps a good compromise at this point would to implement the
ID-matching methods to consider both the ID and the feature object so
that the feature object could be used as the ID in the lookup methods.
IItemPropertyDescriptor propertyDescriptor =
**AdapterFactoryItemDelegator**.getPropertyDescriptor(Middle waresFactory.eINSTANCE.createMiddleware(),
MiddlewaresPackage.Literals.*MIDDLEWARE__NAME*);
What do you think? It's easy enough do implement and I can't imagine
adding such support breaking anything...
>
>
> here is the class :
> public class EmfFormTextRow {
> // Required to allow space for field decorations
> public static final int CONTROL_HORIZONTAL_INDENT = 3;
> private EditingDomain editingDomain;
> private ISWTObservableValue textObservable;
> private Binding textBinding;
> private DataBindingContext bindingContext;
> private IItemPropertyDescriptor propertyDesc;
>
> /**
> * create the adapter class to the EMF feature
> */
> public EmfFormTextRow(EditingDomain editingDomain,
> IItemPropertyDescriptor propertyDescriptor, DataBindingContext
> bindingContext) {
> this.editingDomain = editingDomain;
> this.propertyDesc = propertyDescriptor;
> this.bindingContext = bindingContext;
> }
>
>
> public void createContents(Composite parent, FormToolkit toolkit,
> int span) {
> createLabel(parent, toolkit);
> Text text = toolkit.createText(parent, "", SWT.SINGLE);
> //$NON-NLS-1$
> text.setLayoutData(createGridData(span));
> textObservable = SWTObservables.observeText(text, SWT.Modify);
> }
>
> /**
> * @param parent
> * @param toolkit
> */
> private void createLabel(Composite parent, FormToolkit toolkit) {
> Label label = toolkit.createLabel(parent,
> propertyDesc.getDisplayName(null), SWT.NONE);
> // Label label = toolkit.createLabel(parent, feature.getName(),
> SWT.NONE);
>
> label.setForeground(toolkit.getColors().getColor(IFormColors .TITLE));
> }
>
> protected GridData createGridData(int span) {
> GridData gd = new GridData(span == 2 ?
> GridData.FILL_HORIZONTAL : GridData.HORIZONTAL_ALIGN_FILL);
> gd.widthHint = 20;
> gd.horizontalSpan = span - 1;
> gd.horizontalIndent = CONTROL_HORIZONTAL_INDENT;
> return gd;
> }
>
> public void modelChanged(EObject emfObject) {
> if (textBinding != null) {
> textBinding.dispose();
> }
> IObservableValue source =
> EMFEditObservables.observeValue(editingDomain, emfObject,
> (EStructuralFeature) propertyDesc.getFeature(emfObject));
> textBinding = bindingContext.bindValue(textObservable, source,
> new UpdateValueStrategy(UpdateValueStrategy.POLICY_UPDATE), new
> UpdateValueStrategy(UpdateValueStrategy.POLICY_UPDATE));
> }
>
> /**
> * remove the binding between text control and the emf object
> */
> public void dispose() {
> if (textBinding != null) {
> textBinding.dispose();
> }
> }
>
> /**
> * set the focus to the text control
> */
> public void setFocus() {
> if (textObservable != null) {
> ((Text) textObservable.getWidget()).setFocus();
> }
> }
> }
>
>
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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Comments below.<br>
<br>
SeB.fr wrote:
<blockquote
cite="mid:d404a195704fbec2764749732e7363d1$1@www.eclipse.org"
type="cite">I too had the same problem and found the same solution.
<br>
My use case was to build a generic text editor to include in a Form
using databinding (see the class below).
<br>
<br>
The class is instanciated with a IItemPropertyDescriptor in order to
get the label and the feature.
<br>
in order to get the IItemPropertyDescriptor of one of my model feature
I use the folowing which uses the feature name as the ID:
<br>
IItemPropertyDescriptor propertyDescriptor =
**AdapterFactoryItemDelegator**.getPropertyDescriptor(Middle waresFactory.eINSTANCE.createMiddleware(),
MiddlewaresPackage.Literals.MIDDLEWARE__NAME.getName());
<br>
</blockquote>
IItemPropertyDescriptor has a getFeature method so you could match by
feature.
Ed Merks
Professional Support: https://www.macromodeling.com/
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