Tcl_CreateMathFunc(3) Tcl Library ProceduresTcl_CreateMathFunc(3)_________________________________________________________________NAMETcl_CreateMathFunc - Define a new math function for
expressions
SYNOPSIS
#include <tcl.h>
Tcl_CreateMathFunc(interp, name, numArgs, argTypes, proc, clientData)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter in
which new function
will be defined.
char *name (in) Name for new func-
tion.
int numArgs (in) Number of arguments
to new function;
also gives size of
argTypes array.
Tcl_ValueType *argTypes (in) Points to an array
giving the permis-
sible types for
each argument to
function.
Tcl_MathProc *proc (in) Procedure that
implements the
function.
ClientData clientData (in) Arbitrary one-word
value to pass to
proc when it is
invoked.
_________________________________________________________________DESCRIPTION
Tcl allows a number of mathematical functions to be used
in expressions, such as sin, cos, and hypot. Tcl_Cre-
ateMathFunc allows applications to add additional func-
tions to those already provided by Tcl or to replace
existing functions. Name is the name of the function as
it will appear in expressions. If name doesn't already
exist as a function then a new function is created. If it
does exist, then the existing function is replaced.
NumArgs and argTypes describe the arguments to the func-
tion. Each entry in the argTypes array must be either
TCL_INT, TCL_DOUBLE, or TCL_EITHER to indicate whether the
corresponding argument must be an integer, a double-
Tcl 7.0 1
Tcl_CreateMathFunc(3) Tcl Library ProceduresTcl_CreateMathFunc(3)
precision floating value, or either, respectively.
Whenever the function is invoked in an expression Tcl will
invoke proc. Proc should have arguments and result that
match the type Tcl_MathProc:
typedef int Tcl_MathProc(
ClientData clientData,
Tcl_Interp *interp,
Tcl_Value *args,
Tcl_Value *resultPtr);
When proc is invoked the clientData and interp arguments
will be the same as those passed to Tcl_CreateMathFunc.
Args will point to an array of numArgs Tcl_Value struc-
tures, which describe the actual arguments to the func-
tion:
typedef struct Tcl_Value {
Tcl_ValueType type;
long intValue;
double doubleValue;
} Tcl_Value;
The type field indicates the type of the argument and is
either TCL_INT or TCL_DOUBLE. It will match the argTypes
value specified for the function unless the argTypes value
was TCL_EITHER. Tcl converts the argument supplied in the
expression to the type requested in argTypes, if that is
necessary. Depending on the value of the type field, the
intValue or doubleValue field will contain the actual
value of the argument.
Proc should compute its result and store it either as an
integer in resultPtr->intValue or as a floating value in
resultPtr->doubleValue. It should set also
resultPtr->type to either TCL_INT or TCL_DOUBLE to indi-
cate which value was set. Under normal circumstances proc
should return TCL_OK. If an error occurs while executing
the function, proc should return TCL_ERROR and leave an
error message in interp->result.
KEYWORDS
expression, mathematical function
Tcl 7.0 2
