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Posted to users@daffodil.apache.org by ji...@gmail.com, ji...@gmail.com on 2018/07/12 13:48:01 UTC

Is there a way to reuse a structure but with a different name?

It seems DFDL is very verbose. I have to copy and paste a lot of lines to reuse a structure definition.
Or am I missing a trick? I can do this with simple types.

<!-- Register instance - Current usage --->
<xs:element name="AP_Input" >
    <xs:complexType>
         <xs:sequence>
             <xs:element  ref="register" >
         </xs:sequence>
      </xs:complexType>
</xs:element>

<!-- WISH: Register instance - compact form-->
                    <xs:element name="AP_Input" type="register" >

<!-- register structure definition -->
<xs:element name="register" >
     <xs:complexType>
         <xs:sequence>
             <xs:element name="App_Slot"  type="xs:unsignedByte"/>
             <xs:element name="App_Array" type="xs:unsignedByte"/>
              <xs:element name="App_Index" type="xs:unsignedShort"/>
         </xs:sequence>
      </xs:complexType>
</xs:element>

****************** Expected output:
<AP_Input>
   <register>
      <App_Slot>0</App_Slot>
      <App_Array>0</App_Array>
      <App_Index>0</App_Index>
  </register>
</AP_Input>

Re: Is there a way to reuse a structure but with a different name?

Posted by Mike Beckerle <mb...@tresys.com>.
The trick you need is using a named complex type definition, and/or a named group definition.


E.g.,


<xs:element name="AP_Input" type="registerType"/>


<xs:complexType name="registerType">

   <xs:sequence>

        <xs:element name="App_Slot"  type="xs:unsignedByte"/>
        <xs:element name="App_Array" type="xs:unsignedByte"/>
        <xs:element name="App_Index" type="xs:unsignedShort"/>

   </xs:sequence>

</xs:complexType>


If you want to reuse groups of fields within various types, you can use named groups for that. E.g.,


<xs:group name="registerGroup">

   <xs:sequence>

        <xs:element name="App_Slot"  type="xs:unsignedByte"/>
        <xs:element name="App_Array" type="xs:unsignedByte"/>
        <xs:element name="App_Index" type="xs:unsignedShort"/>

   </xs:sequence>

</xs:group>


Then you use this with a group reference from within as many named complex types as you want.


<xs:complexType name="registerType">

   <xs:group ref="registerGroup"/>

</xs:complexType>


<xs:complexType name="someOtherType">

   <xs:sequence>

     <xs:group ref="registerGroup" />

      ... reference other reusable groups of fields here too, or define directly here.

    </xs:sequence>

 </xs:complexType>


In general anywhere you can put a xs:sequence or xs:element you can put a xs:group reference.


So I think one can avoid the troublesome repetition of definitions you were trying to avoid.


-Mike Beckerle

Tresys


________________________________
From: jimwelchok@gmail.com <ji...@gmail.com>
Sent: Thursday, July 12, 2018 9:48:01 AM
To: users@daffodil.apache.org
Subject: Is there a way to reuse a structure but with a different name?

It seems DFDL is very verbose. I have to copy and paste a lot of lines to reuse a structure definition.
Or am I missing a trick? I can do this with simple types.

<!-- Register instance - Current usage --->
<xs:element name="AP_Input" >
    <xs:complexType>
         <xs:sequence>
             <xs:element  ref="register" >
         </xs:sequence>
      </xs:complexType>
</xs:element>

<!-- WISH: Register instance - compact form-->
                    <xs:element name="AP_Input" type="register" >

<!-- register structure definition -->
<xs:element name="register" >
     <xs:complexType>
         <xs:sequence>
             <xs:element name="App_Slot"  type="xs:unsignedByte"/>
             <xs:element name="App_Array" type="xs:unsignedByte"/>
              <xs:element name="App_Index" type="xs:unsignedShort"/>
         </xs:sequence>
      </xs:complexType>
</xs:element>

****************** Expected output:
<AP_Input>
   <register>
      <App_Slot>0</App_Slot>
      <App_Array>0</App_Array>
      <App_Index>0</App_Index>
  </register>
</AP_Input>