wpclsQueryInstanceFilter
This method is called to allow the class object to specify the file title filters for instances of its class.
Syntax
_wpclsQueryInstanceFilter(somSelf)
Parameters
- somSelf (M_WPFileSystem *) - input
- Pointer to the WPFileSystem class object.
- psuccess (PSZ) - returns
- Success indicator. NULL Error occurred. Other A pointer to a string containing file title filters. This string can contain several file title filters separated by commas. For example: '*.TXT, *.DOC'.
Returns
- psuccess (PSZ) - returns
- Success indicator. NULL Error occurred. Other A pointer to a string containing file title filters. This string can contain several file title filters separated by commas. For example: '*.TXT, *.DOC'.
Remarks
It is important that the values returned by this class method are restricted to class-specific filters. For example, returning a filter of *.* could effectively make the system unstable.
How to Override
This method should be overridden in order to automatically designate file objects as instances of this class. The value returned by the override method will replace the current title filter string which is used to designate instances. If the parent method is called, it should be called first.
Usage
This method can be called at any time in order to determine which file title filters are used to determine instances of this class.
Example Code
Declaration:
#define INCL_WINWORKPLACE #include <os2.h> M_WPFileSystem *somSelf; /* Pointer to the WPFileSystem class object. */ PSZ psuccess; /* Success indicator. */ psuccess = _wpclsQueryInstanceFilter(somSelf);
This example shows how to designate files ending in an extension of .GIF as being associated with an instance of a GIFPicture object.
SOM_Scope PSZ SOMLINK gifpicM_wpclsQueryInstanceFilter(M_GIFPicture *somSelf)
{
/* M_GIFPictureData *somThis = M_GIFPictureGetData(somSelf); */
M_GIFPictureMethodDebug('M_GIFPicture','gifpicM_wpclsQueryInstanceFilter');
/* return (parent_wpclsQueryInstanceFilter(somSelf)); Don't call parent */
return ( '*.GIF' );
}