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XmtSymbolAddCallback(3)	   Library Functions Manual    XmtSymbolAddCallback(3)

NAME
       XmtSymbolAddCallback(),	XmtSymbolRemoveCallback()  -  add and remove a
       procedure to be called when a symbol's value changes.

SYNOPSIS
       #include	<Xmt/Symbols.h>

       void XmtSymbolAddCallback(XmtSymbol s, XmtSymbolCallbackProc proc,
		      XtPointer	client_data)

       void XmtSymbolRemoveCallback(XmtSymbol s, XmtSymbolCallbackProc proc,
		      XtPointer	client_data)

       typedef void (*XmtSymbolCallbackProc)(XmtSymbol s, XtPointer
		      client_data, XtArgVal value);

ARGUMENTS
       INPUTS

	    s	   An  XmtSymbol  for  which  the  callback  is	to be added or
		   removed.

	    proc   The procedure to be added or	removed.

	    client_data
		   An untyped data value registered (or	 removed)  with	 proc,
		   and	which is passed	as the second argument to proc when it
		   is invoked.

	    value  The untyped value of	 the  symbol.  This  argument  is  not
		   passed  to  XmtSymbolAddCallback()  or XmtSymbolRemoveCall-
		   back(), but it is the third argument	passed to  the	regis-
		   tered XmtSymbolCallbackProc proc when it is invoked.

DESCRIPTION
       XmtSymbolAddCallback()  registers the procedure proc to be invoked with
       the specified client_data whenever the value of symbol s	changes.

       XmtSymbolRemoveCallback() unregisters  the  proc/client_data  pair  for
       symbol  s.  This	 procedure will	no longer be called with the specified
       client_data when	the value of s is updated.

       proc is an XmtSymbolCallbackProc. It will be invoked with  three	 argu-
       ments.  The  first  argument to a symbol	callback is the	XmtSymbol that
       has had its value changed. The  second  argument	 is  whatever  untyped
       client_data  was	 registered with the callback procedure, and the third
       argument, value,	is the new value of the	symbol.	 This  is  either  the
       value  itself,  or, if the value	is too large to	fit in an XtArgVal (or
       if it is	of type	XmtRBuffer), it	is a pointer to	the value.

SEE ALSO
       Chapter 12, Symbols,
       XmtLookupSymbol(), XmtSymbolGetValue(), XmtSymbolSetValue(),
       XmtSymbolSetTypedValue(), XmtVaRegisterSymbols().

Xmt				  Motif	Tools	       XmtSymbolAddCallback(3)

NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | SEE ALSO

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