Xerox -05W - Manual (Page 305)

13-13
Dynamic Data Exchange
/* Treat Key macro request as a special case */
if (MenuID == IDM_MACROS)
lSetting = MAKELONG(-DataGroup,iValue);
else
lSetting = MAKELONG(DataGroup,MenuID);
ultoa(lSetting,buf,10);
aItem = GlobalAddAtom((LPSTR)buf);
if (!PostMessage(
hWndPartnerDDE,
WM_DDE_REQUEST,
hWndSlaveDDE,
MAKELONG(CF_TEXT,aItem)
)
)
{
GlobalDeleteAtom(atomItem);
return -1;
}
/* Wait for DDE_DATA message return with requested data */
Xfer.Parameter = TRUE;
WaitForParameter();
return Xfer.Data;
}
The WaitForParameter function is not documented but basically waits in a loop,
monitoring the windows messages until a WM_DDE_DATA message appears that
corresponds to the initial WM_DDE_REQUEST. This then enables the
RequestSetting procedure to return with the appropriate value, or will return -1 if the
request fails. (This would be caused as a result of the Client Slave process receiving a
negative ACKnowledgement from TeemTalk following receipt of the
WM_DDE_REQUEST message.)
The processing of the WM_DDE_DATA message is shown on the next page.