View source for SomDataResolveChk

{{DISPLAYTITLE:somDataResolveChk}}
This function accesses instance data within an object. 

==Syntax==
<PRE>
SOMObject    obj;
somDToken    dToken;
somToken     rc;

rc = somDataResolveChk(obj, dToken);
</PRE>
==Parameters==
;obj (SOMObject) : A pointer to the object whose instance data is required.
;dToken (somDToken) : A data token for the required instance data. The SOM API specifies that the data token for accessing the instance data introduced by a class is found in the instanceDataToken component of the auxiliary class data structure for that class. The example below illustrates this.

==Return Code==
;rc (somToken) : A somToken (that is, a pointer) that points to the data in obj identified by the dToken. If obj does not contain the requested data identified by dToken, somDataResolveChk returns NULL.

==Remarks==
The somDataResolveChk function is used to access instance data within an object. This function is of use primarily to class implementors (rather than class clients) who are not using the SOM C or C++ language bindings.

For C or C++ programmers with access to the C or C++ implementation bindings for a class, instance data can be accessed using the GetData macro (which expands to a usage of somDataResolve). 

==Example Code==
The following C/C++ expression evaluates to the address of the instance data introduced by class "XYZ" within the object "obj". This assumes that obj points to an instance of "XYZ" or a subclass of "XYZ". 
 #include <som.h>
 somDataResolveChk(obj, XYZCClassData.instanceDataToken);

===Related Data Structures===
*somToken (sombtype.h)
*[[SOMObject]] (somobj.idl)
*somDToken (somapi.h)

[[Category:SOM Kernel]]