textCallBack - Maple Programming Help

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textCallBack

handle text output in OpenMaple

 Calling Sequence textCallBack(data, tag, output)

Parameters

 data - user_data pointer passed to StartMaple (Long) tag - code indicating kind of text (Long) output - output string (byte array pointer)

Description

 • This OpenMaple function is part of the MapleCallBack structure passed as an argument to StartMaple.
 • The textCallBack function is called with typical (non-exceptional) Maple output. The output that Maple generates, for example, an intermediate result or the output from a printf statement, is passed to the textCallBack function.
 • The prototype for the function that you can assign to the entry in the MapleCallBack must resemble the following.

 Sub TextCallBack(ByVal data As Long, ByVal tag As Integer, ByVal Output As Long)

 • The tag parameter indicates the type of Maple output. The tag parameter can take one of the following values (as defined in maplec.h).

 MAPLE_TEXT_OUTPUT A line-printed (1-D) Maple expression or statement. MAPLE_TEXT_DIAG Diagnostic output (high printlevel or trace output). MAPLE_TEXT_MISC Miscellaneous output, for example, from the Maple printf function. MAPLE_TEXT_QUIT Response to a Maple quit, done, or stop command. MAPLE_TEXT_WARNING A warning message generated during a computation. MAPLE_TEXT_ERROR An error message generated during parsing or processing. This is generated only if you do not specify an errorCallBack function. MAPLE_TEXT_STATUS Kernel resource usage status (a "bytes used" message). This is generated only if you do not specify a statusCallBack function. MAPLE_TEXT_DEBUG Output from the Maple debugger.

 • The output parameter contains the output of the type indicated by the tag parameter. Each output string can be arbitrarily long.  Most output obeys interface(screenwidth), which is initially set to infinity.  Some output is not line-broken, including output generated by printf (which controls its own formatting).
 • A single result may be split into multiple calls to the textCallBack function. In particular, this can happen when $\mathrm{interface}\left(\mathrm{screenwidth}\right)$ is not infinity.  It is also true for formatted output like that generated by accessing help.  A single command can generate many calls with different output tags.
 • The data parameter contains the same data as passed to StartMaple in the user_data parameter.

Examples

 Public Sub TextCallBack2(ByVal data As Long, ByVal tag As Integer, _ ByVal Output As Long) Dim OutputString As String OutputString = MaplePointerToString(Output) If tag = MAPLE_TEXT_HELP Then Write #2, OutputString Else Write #1, OutputString End If End Sub ' assignment to MapleCallback entry cb.lpTextCallBack = GetProc(AddressOf TextCallBack) ' test statement that will invoke the TextCallBack EvalMapleStatement kv, "x^2+3*x+1;" EvalMapleStatement kv, "help(int);"