Programmer's Reference


Platform-specific support

The IBM Smalltalk DDE subsystem was developed as an extension to the DDE support provided by IBM OS/2 and Microsoft Windows. The following figure illustrates the layers provided by the IBM Smalltalk DDE subsystem.
IBM Smalltalk DDE support

The application programmer can skip the provided IBM Smalltalk DDE layer and program directly to the operating system support mechanisms in the platform interface layer.

In the platform interface layer, objects have been created for all C data types for both IBM OS/2 and Microsoft Windows. These data types include items such as DDEACK, DDEADVISE, DDEDATA, and HWND for Microsoft Windows, or DDEINIT, DDESTRUCT, CONVCONTEXT, and HWND for IBM OS/2. These data objects are named by prefixing the data type name with OS, and applying bicapitalization rules. For example, HWND becomes OSHwnd. Additionally, each operating system C function has been converted to a corresponding Smalltalk method. To understand this conversion, consider the standard OS/2 function WinDdePostMsg:

WinDdePostMsg( hwndDest, hwndSource, msg, ddeStruct, 1)

This function has been converted to the following:

OSHwnd>>winDdePostMsg: hwndFrom wm: wm pddest:pddest
   flOptions:flOptions

In translating C functions to Smalltalk, two rules have been applied:


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