/*
*
* METHOD: QueryInfo PRIVATE
*
* PURPOSE: Copy the PWFolder instance data into
* the PWF_INFO structure that pPWFolderInfo
* points to.
* ┌─────2
*/ │ ┌──────3
.
SOM_Scope BOOL SOMLINK pwFolder_QueryInfo(PWFolder *somSelf,
PPWF_INFO pPWFolderInfo)
{ └───1
PWFolderData *somThis = PWFolderGetData(somSelf); 4
PWFolderMethodDebug("PWFolder","pwfolder_QueryInfo"); 5
<application logic> 6
return((BOOL)0);
}
└────7
Notes:
1 SOM_Scope declares the function scope according to the language being used. For example, in C++, SOM_Scope would be defined as extern C but in C it is simply defined as extern.
2 It can be seen that the external prefix "pwfolder_", which was specified in the class definition file, has been placed in front of the function as expected. Note that the SOM Precompiler generates a macro for this function in the private header file:
#define _QueryInfo PWFolder_QueryInfo
This avoids the necessity for the programmer to type the full function name, and helps make the code more readable.
3 Since SOM uses the C language, methods from SOM objects cannot be referenced in a very elegant manner. The first parameter to a SOM method must be a pointer to an object that can invoke that method. In the actual method function, this pointer is given the name somSelf. For example, the difference between C and C++ is as follows:
/* Let us say */
pMyObject = (pointer to an object);
// in C++ the following syntax may be used
pMyObject->Method(param1, param2....);
/* but in C the following is required */
Method(pMyObject, param1, param2....);
4 This statement uses the pointer to the object to initialize a pointer to access the object's instance data. See Methods (Method Processing and Instance Data) for further information on instance data.
5 This line will perform tracing. Tracing is switched on whenever the SOM global variable SOM_TraceLevel is set to a non-zero value.
6 This section is left blank by the SOM Precompiler for the developer to fill with the applicaton logic. This logic may include access to system and/or Presentation Manager resources. For the password-protected folder example, the _QueryInfo method must copy the instance variables to the PWF_INFO data structure defined in the passthru section of the class definition file. The code required to do this is as follows:
strcpy(pPWFolderInfo->szPassword, _szPassword); strcpy(pPWFolderInfo->szCurrentPassword, _szCurrentPassword); strcpy(pPWFolderInfo->szUserid, _szUserid);
This code must be inserted in the C source file by the programmer, after the file is generated by the SOM Precompiler. This may be done using a normal text editor.
7 Finally, the SOM Precompiler provides a default zero return statement, typecast with the return data type of the method as declared in the methods section of the class definition file. This statement may be altered by the programmer if required, provided that consistency with the method's prototype and declaration is maintained.