Tcl_CreateMathFunc(3) Tcl (7.0) 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 function will be
defined.
char *name (in) Name for new
function.
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
permissible 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.
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DESCRIPTION
Tcl allows a number of mathematical functions to be used in
expressions, such as sin, cos, and hypot.
Tcl_CreateMathFunc allows applications 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 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 function. Each entry
in the argTypes array must be either TCL_INT, TCL_DOUBLE, or
TCL_EITHER to indicate whether the corresponding argument
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Tcl_CreateMathFunc(3) Tcl (7.0) Tcl_CreateMathFunc(3)
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 arguments 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 interp-
>result.
KEYWORDS
expression, mathematical function
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