CrtMathFnc
Tcl_CreateMathFunc(3) Tcl Library Procedures Tcl_CreateMathFunc(3)
______________________________________________________________________________
NAME
Tcl_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 func-
tion will be defined.
char *name (in) Name for new function.
int numArgs (in) Number of arguments to new func-
tion; also gives size of
argTypes array.
Tcl_ValueType *argTypes (in) Points to an array giving the
permissible types for each argu-
ment 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 expres-
sions, such as sin, cos, and hypot. Tcl_CreateMathFunc allows applica-
tions to add additional functions 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 func-
tion then a new function is created. If it does exist, then the exist-
ing function is replaced. NumArgs and argTypes describe the arguments
to the function. Each entry in the argTypes array must be either
TCL_INT, TCL_DOUBLE, or TCL_EITHER to indicate whether the correspond-
ing argument must be an integer, a double-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 structures, which describe the actual argu-
ments to the function:
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
indicate 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 the interpreter's
result.
KEYWORDS
expression, mathematical function
Tcl 7.0 Tcl_CreateMathFunc(3)
