163 lines
6.9 KiB
Groff
163 lines
6.9 KiB
Groff
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'\"
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'\" Copyright (c) 1989-1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH Tcl_CreateMathFunc 3 8.4 Tcl "Tcl Library Procedures"
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.so man.macros
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.BS
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.SH NAME
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Tcl_CreateMathFunc, Tcl_GetMathFuncInfo, Tcl_ListMathFuncs \- Define, query and enumerate math functions for expressions
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.SH "NOTICE OF EVENTUAL DEPRECATION"
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.PP
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The \fBTcl_CreateMathFunc\fR and \fBTcl_GetMathFuncInfo\fR functions
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are rendered somewhat obsolete by the ability to create functions for
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expressions by placing commands in the \fBtcl::mathfunc\fR namespace,
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as described in the \fBmathfunc\fR manual page; the API described on
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this page is not expected to be maintained indefinitely.
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.SH SYNOPSIS
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.nf
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\fB#include <tcl.h>\fR
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.sp
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void
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\fBTcl_CreateMathFunc\fR(\fIinterp, name, numArgs, argTypes, proc, clientData\fR)
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.sp
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int
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\fBTcl_GetMathFuncInfo\fR(\fIinterp, name, numArgsPtr, argTypesPtr, procPtr,
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clientDataPtr\fR)
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.sp
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Tcl_Obj *
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\fBTcl_ListMathFuncs\fR(\fIinterp, pattern\fR)
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.SH ARGUMENTS
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.AS Tcl_ValueType *clientDataPtr out
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.AP Tcl_Interp *interp in
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Interpreter in which new function will be defined.
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.AP "const char" *name in
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Name for new function.
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.AP int numArgs in
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Number of arguments to new function; also gives size of \fIargTypes\fR array.
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.AP Tcl_ValueType *argTypes in
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Points to an array giving the permissible types for each argument to
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function.
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.AP Tcl_MathProc *proc in
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Procedure that implements the function.
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.AP ClientData clientData in
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Arbitrary one-word value to pass to \fIproc\fR when it is invoked.
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.AP int *numArgsPtr out
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Points to a variable that will be set to contain the number of
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arguments to the function.
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.AP Tcl_ValueType **argTypesPtr out
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Points to a variable that will be set to contain a pointer to an array
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giving the permissible types for each argument to the function which
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will need to be freed up using \fITcl_Free\fR.
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.AP Tcl_MathProc **procPtr out
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Points to a variable that will be set to contain a pointer to the
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implementation code for the function (or NULL if the function is
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implemented directly in bytecode).
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.AP ClientData *clientDataPtr out
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Points to a variable that will be set to contain the clientData
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argument passed to \fITcl_CreateMathFunc\fR when the function was
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created if the function is not implemented directly in bytecode.
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.AP "const char" *pattern in
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Pattern to match against function names so as to filter them (by
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passing to \fITcl_StringMatch\fR), or NULL to not apply any filter.
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.BE
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.SH DESCRIPTION
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.PP
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Tcl allows a number of mathematical functions to be used in
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expressions, such as \fBsin\fR, \fBcos\fR, and \fBhypot\fR.
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These functions are represented by commands in the namespace,
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\fBtcl::mathfunc\fR. The \fBTcl_CreateMathFunc\fR function is
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an obsolete way for applications to add additional functions
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to those already provided by Tcl or to replace existing functions.
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It should not be used by new applications, which should create
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math functions using \fBTcl_CreateObjCommand\fR to create a command
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in the \fBtcl::mathfunc\fR namespace.
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.PP
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In the \fBTcl_CreateMathFunc\fR interface,
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\fIName\fR is the name of the function as it will appear in expressions.
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If \fIname\fR does not already exist in the \fB::tcl::mathfunc\fR
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namespace, then a new command is created in that namespace.
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If \fIname\fR does exist, then the existing function is replaced.
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\fINumArgs\fR and \fIargTypes\fR describe the arguments to the function.
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Each entry in the \fIargTypes\fR array must be
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one of \fBTCL_INT\fR, \fBTCL_DOUBLE\fR, \fBTCL_WIDE_INT\fR,
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or \fBTCL_EITHER\fR to indicate whether the corresponding argument must be an
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integer, a double-precision floating value, a wide (64-bit) integer,
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or any, respectively.
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.PP
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Whenever the function is invoked in an expression Tcl will invoke
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\fIproc\fR. \fIProc\fR should have arguments and result that match
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the type \fBTcl_MathProc\fR:
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.PP
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.CS
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typedef int \fBTcl_MathProc\fR(
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ClientData \fIclientData\fR,
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Tcl_Interp *\fIinterp\fR,
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Tcl_Value *\fIargs\fR,
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Tcl_Value *\fIresultPtr\fR);
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.CE
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.PP
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When \fIproc\fR is invoked the \fIclientData\fR and \fIinterp\fR
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arguments will be the same as those passed to \fBTcl_CreateMathFunc\fR.
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\fIArgs\fR will point to an array of \fInumArgs\fR Tcl_Value structures,
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which describe the actual arguments to the function:
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.PP
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.CS
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typedef struct Tcl_Value {
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Tcl_ValueType \fItype\fR;
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long \fIintValue\fR;
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double \fIdoubleValue\fR;
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Tcl_WideInt \fIwideValue\fR;
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} \fBTcl_Value\fR;
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.CE
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.PP
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The \fItype\fR field indicates the type of the argument and is
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one of \fBTCL_INT\fR, \fBTCL_DOUBLE\fR or \fBTCL_WIDE_INT\fR.
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It will match the \fIargTypes\fR value specified for the function unless
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the \fIargTypes\fR value was \fBTCL_EITHER\fR. Tcl converts
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the argument supplied in the expression to the type requested in
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\fIargTypes\fR, if that is necessary.
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Depending on the value of the \fItype\fR field, the \fIintValue\fR,
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\fIdoubleValue\fR or \fIwideValue\fR
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field will contain the actual value of the argument.
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.PP
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\fIProc\fR should compute its result and store it either as an integer
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in \fIresultPtr->intValue\fR or as a floating value in
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\fIresultPtr->doubleValue\fR.
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It should set also \fIresultPtr->type\fR to one of
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\fBTCL_INT\fR, \fBTCL_DOUBLE\fR or \fBTCL_WIDE_INT\fR
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to indicate which value was set.
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Under normal circumstances \fIproc\fR should return \fBTCL_OK\fR.
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If an error occurs while executing the function, \fIproc\fR should
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return \fBTCL_ERROR\fR and leave an error message in the interpreter's result.
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.PP
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\fBTcl_GetMathFuncInfo\fR retrieves the values associated with
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function \fIname\fR that were passed to a preceding
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\fBTcl_CreateMathFunc\fR call. Normally, the return code is
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\fBTCL_OK\fR but if the named function does not exist, \fBTCL_ERROR\fR
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is returned and an error message is placed in the interpreter's
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result.
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.PP
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If an error did not occur, the array reference placed in the variable
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pointed to by \fIargTypesPtr\fR is newly allocated, and should be
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released by passing it to \fBTcl_Free\fR. Some functions (the
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standard set implemented in the core, and those defined by placing
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commands in the \fBtcl::mathfunc\fR namespace) do not have
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argument type information; attempting to retrieve values for
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them causes a NULL to be stored in the variable pointed to by
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\fIprocPtr\fR and the variable pointed to by \fIclientDataPtr\fR
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will not be modified. The variable pointed to by \fInumArgsPointer\fR
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will contain -1, and no argument types will be stored in the variable
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pointed to by \fIargTypesPointer\fR.
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.PP
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\fBTcl_ListMathFuncs\fR returns a Tcl value containing a list of all
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the math functions defined in the interpreter whose name matches
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\fIpattern\fR. The returned value has a reference count of zero.
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.SH "SEE ALSO"
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expr(n), info(n), Tcl_CreateObjCommand(3), Tcl_Free(3), Tcl_NewListObj(3)
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.SH KEYWORDS
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expression, mathematical function
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