Details of the .VCX File ArchitectureLast reviewed: April 30, 1996Article ID: Q130085 |
The information in this article applies to:
SUMMARYYou can create classes in Visual FoxPro in a program or in the visual interface. Using the Class Designer to create classes visually produces a table with a .VCX extension. Although it is not necessary to understand the ways in which the .VCX tables store metadata, many developers have reasons for wanting to read and write to these tables. This article shows and explains the file architecture of a .VCX table.
MORE INFORMATIONThe VCX table contains information about the objects in classes.
Field Name Type Example Definition Platform C(8) WINDOWS Associates a specific platform
for an object. In single-platform
tables, every object has one record
per platform. Cross-platform objects
have one record per platform with the
same UniqueID and are distinguished by
the Platform field. For records that
do not relate to a specific class or
object, the Platform field contains
the string "COMMENT." The header
record (record #1) has UniqueID =
Class.
UniqueID C(10) _ QYB0RAW20 Gives unique ID code for individual
classes and objects. Related
cross-platform records share the same
UniqueID value. For records that do
not relate to a specific class or
object, the UniqueID field contains
information that describes the type
of record. The header record
(record #1) has UniqueID = "Class."
TimeStamp N(10) 495748740 Relates directly to the date and time
the object symbols were created or
last generated. The TimeStamp field
for all records associated with a
class are updated whenever the class
is changed. For records that do not
relate to a specific class or object,
TimeStamp=0.
Class Memo mycommandbutton Defines which class is used to create
the subclass of the class or object
member.
ClassLoc Memo tsbase.vcx Gives relative path and filename of
class defined in the Class field. If
the Class field specifies a Visual
FoxPro built-in base class or the
Class name specified is located in the
same VCX, then the ClassLoc field is
empty.
BaseClass Memo commandbutton Stores the name of the base class, or
topmost parent class in the class tree
hierarchy, of the class or object
member.
ObjName Memo cmdCancel Defines the name of the class or
object member.
Parent Memo form1 References the immediate parent
container object that the object is a
member of. If an object member is not
a child member of a container, the
Parent field is empty.
Properties Memo Height=22 Lists properties and their set values
Width=69 that override the values defined in
FontSize=8 the parent class from which a class or
Caption="Cancel" object member is derived.
Name="cmdcancel"
Protected Memo cAliasdUpdated Lists all properties and methods that
are marked as protected members for a
class.
Methods Memo PROCEDURE Click Contains all snippet code of a class
thisform.Release() or object member.
ENDPROC
ObjCode Memo Stores the compiled p-code of source
code stored in the Methods field.
ObjCode is empty if the Methods field
is empty.
Ole Memo Stores binary information for OLE
class and object members.
Ole2 Memo Stores binary information for OLE
class and object members.
Reserved1 Memo Class Uses Class tag field to indicate the
start of a class definition by storing
the string "Class." If a record is not
the start of a class definition, the
Reserved1 field is empty.
Reserved2 Memo 2 Stores the number of records
associated with a class, including the
class or container record. This field
only contains a value for the first
record of a class definition. If a
class doesn't contain any object
members, the Reserved2 field for the
record that starts the class
definition contains a 1. For records
that are not the start of a class
definition, the Reserved2 field is
empty.
Reserved3 Memo cAlias Lists all user-defined member names of
nResultd a class with the member description
Updated separated by a single space character.
cMyProperty One member is stored with its
^aNames[5] description per memo line. Standard
^aMyArray[100] property names are listed without a
*Print preceding character, array properties
*SortNames are preceded with a caret (^), and
*MyMethod method names are preceded with an
asterisk (*).
Reserved4 Memo bmps\cancel.bmp Stores the relative path and filename
of the bitmap (.BMP) of a custom class
icon.
Reserved5 Memo bmps\cancel.bmp Stores the relative path and filename
of the bitmap (.BMP) for a custom
Project Manager and Class Browser
class icon.
Reserved6 Memo Pixels Stores scalemode (Pixels/Foxels) of a
class or object.
Reserved7 Memo This class Stores a class description that can be
releases the modified within the Class Info...
form dialog of the Class Designer.
Reserved8 Memo ..\vfp\FoxPro.h Stores the relative path and filename
of the #INCLUDE file for all snippets.
User Memo Remains open for user-defined
purposes.
REFERENCESInformation in this article was obtained from "Visual FoxPro's VCX and SCX Architectures" by Ken Levy in the March 1995 issue of FoxTalk.
|
Additional reference words: 3.00 structure architecture VFoxWin
© 1998 Microsoft Corporation. All rights reserved. Terms of Use. |