CDocument

CDocument is a class in the Microsoft Foundation Classes (MFC) library that serves as the data model in the Document/View architecture. It is the base class from which applications derive their own document types, encapsulating the data and its persistence logic separate from the user interface.

The primary role of CDocument is to store and manage the application's document data. It provides core facilities for document lifecycle management, including creation of new documents, opening existing ones, and saving changes. A key feature is serialization, implemented through the virtual Serialize(CArchive& ar) method, which reads and writes the document’s data to and from a stream. Derived classes override Serialize to define how their specific data is persisted.

CDocument also maintains metadata about the document, such as its file path (GetPathName, SetPathName) and display title (GetTitle, SetTitle). It tracks modification state with a modified flag, accessible via IsModified and SetModifiedFlag, enabling the framework to prompt for saves when needed.

In the MFC Document/View framework, the document object coordinates with one or more view objects to reflect data changes in the user interface. When data changes, the document typically calls UpdateAllViews to notify associated views so they can redraw. The framework also uses document templates (CMultiDocTemplate, CSingleDocTemplate) to bind a document class to its corresponding frame and view classes, supporting single-document or multiple-document interfaces.

Developers typically derive their own document class from CDocument, adding application-specific data members and implementing or extending serialization as required. CDocument provides a structured foundation for persistent, editable data separate from presentation logic, while remaining flexible for custom behavior.