| XSD ItemProviders should use EMF pattern for creating PropertyDescriptors [message #580413] |
Wed, 05 November 2003 01:07 |
 Randall Hauch
Messages: 79
Registered: July 2009 |
Member |
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This is a multi-part message in MIME format.
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This is a suggestion for future versions of the XSD plugins, which were =
originally built with an earlier version of EMF (or its predecessor?).
The newer EMF versions generate ItemProvider implementations in a way =
that makes it very easy to override and extend how the various =
PropertyDescriptor objects are created. The basic approach is that =
there is an "add<featureName>PropertyDescriptor(Object)" method for each =
structural feature defined by the EClass to which the ItemProvider =
corresponds, and the "getPropertyDescriptors(Object)" method simply
a.. calls super.getPropertyDescriptors(obj)
b.. calls each of the "add<featureName>PropertyDescriptor(Object)" =
methods
This is great when just a few of the PropertyDescriptors are to be =
created using different parameters, since you only have to override the =
appropriate "add<featureName>PropertyDescriptor(Object)" methods.
However, few of the ItemProvider implementations are written this way. =
For example, the "getPropertyDescriptors(Object)" method on =
XSDSimpleTypeDefinitionItemProvider actually creates all of the =
PropertyDescriptors in-line, so it's not straightforward to override =
just a few of them.
This is not high-priorty, though, since it is possible in an =
ItemProvider subclass to remove one or more PropertyDescriptors created =
in the superclass implementations and add new forms that better suit =
your need. However, it's just not very straightforward.
Randall
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Diso-8859-1">
<META content=3D"MSHTML 6.00.2800.1264" name=3DGENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>This is a suggestion for future =
versions of the XSD=20
plugins, which were originally built with an earlier version of EMF (or =
its=20
predecessor?).</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>The newer EMF versions generate =
ItemProvider=20
implementations in a way that makes it very easy to override and extend =
how the=20
various PropertyDescriptor objects are created. The basic approach =
is that=20
there is an "add<featureName>PropertyDescriptor(Object)" method =
for each=20
structural feature defined by the EClass to which the ItemProvider =
corresponds,=20
and the "getPropertyDescriptors(Object)" method simply</FONT></DIV>
<UL>
<LI><FONT face=3DArial size=3D2>calls=20
super.getPropertyDescriptors(obj)</FONT></LI>
<LI><FONT face=3DArial size=3D2>calls each of the=20
"add<featureName>PropertyDescriptor(Object)" =
methods</FONT></LI></UL>
<DIV><FONT face=3DArial size=3D2>This is great when just a few of the=20
PropertyDescriptors are to be created using different parameters, since =
you only=20
have to override the appropriate=20
"add<featureName>PropertyDescriptor(Object)" methods.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>However, few of the ItemProvider =
implementations=20
are written this way. For example, the =
"getPropertyDescriptors(Object)"=20
method on XSDSimpleTypeDefinitionItemProvider actually creates all of =
the=20
PropertyDescriptors in-line, so it's not straightforward to override =
just a few=20
of them.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>This is not high-priorty, though, since =
it is=20
possible in an ItemProvider subclass to remove one or more =
PropertyDescriptors=20
created in the superclass implementations and add new forms that better =
suit=20
your need. However, it's just not very =
straightforward.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Randall</FONT></DIV></BODY></HTML>
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