Tribblix: manual page: Tcl

Tcl_CreateMathFunc(3) Tcl Library Procedures Tcl_CreateMathFunc(3)

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NAME

Tcl_CreateMathFunc, Tcl_GetMathFuncInfo, Tcl_ListMathFuncs - Define,
query and enumerate math functions for expressions

NOTICE OF EVENTUAL DEPRECATION

The Tcl_CreateMathFunc and Tcl_GetMathFuncInfo functions are rendered
somewhat obsolete by the ability to create functions for expressions
by placing commands in the tcl::mathfunc namespace, as described in
the mathfunc manual page; the API described on this page is not
expected to be maintained indefinitely.

SYNOPSIS

#include <tcl.h>

void
Tcl_CreateMathFunc(interp, name, numArgs, argTypes, proc, clientData)

int
Tcl_GetMathFuncInfo(interp, name, numArgsPtr, argTypesPtr, procPtr,
clientDataPtr)

Tcl_Obj *
Tcl_ListMathFuncs(interp, pattern)

ARGUMENTS

Tcl_Interp *interp (in) Interpreter in which new
function will be defined.

const 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.

int *numArgsPtr (out) Points to a variable that
will be set to contain the
number of arguments to the
function.

Tcl_ValueType **argTypesPtr (out) Points to a variable that
will be set to contain a
pointer to an array giving
the permissible types for
each argument to the
function which will need
to be freed up using
Tcl_Free.

Tcl_MathProc **procPtr (out) Points to a variable that
will be set to contain a
pointer to the
implementation code for
the function (or NULL if
the function is
implemented directly in
bytecode).

ClientData *clientDataPtr (out) Points to a variable that
will be set to contain the
clientData argument passed
to Tcl_CreateMathFunc when
the function was created
if the function is not
implemented directly in
bytecode.

const char *pattern (in) Pattern to match against
function names so as to
filter them (by passing to
Tcl_StringMatch), or NULL
to not apply any filter.
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DESCRIPTION

Tcl allows a number of mathematical functions to be used in
expressions, such as sin, cos, and hypot. These functions are
represented by commands in the namespace, tcl::mathfunc. The
Tcl_CreateMathFunc function is an obsolete way for applications to
add additional functions to those already provided by Tcl or to
replace existing functions. It should not be used by new
applications, which should create math functions using
Tcl_CreateObjCommand to create a command in the tcl::mathfunc
namespace.

In the Tcl_CreateMathFunc interface, Name is the name of the function
as it will appear in expressions. If name does not already exist in
the ::tcl::mathfunc namespace, then a new command is created in that
namespace. If name 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 one of TCL_INT,
TCL_DOUBLE, TCL_WIDE_INT, or TCL_EITHER to indicate whether the
corresponding argument must be an integer, a double-precision
floating value, a wide (64-bit) integer, or any, 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_WideInt wideValue;
} Tcl_Value;

The type field indicates the type of the argument and is one of
TCL_INT, TCL_DOUBLE or TCL_WIDE_INT. 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, doubleValue or wideValue
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 one of TCL_INT, TCL_DOUBLE or
TCL_WIDE_INT 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.

Tcl_GetMathFuncInfo retrieves the values associated with function
name that were passed to a preceding Tcl_CreateMathFunc call.
Normally, the return code is TCL_OK but if the named function does
not exist, TCL_ERROR is returned and an error message is placed in
the interpreter's result.

If an error did not occur, the array reference placed in the variable
pointed to by argTypesPtr is newly allocated, and should be released
by passing it to Tcl_Free. Some functions (the standard set
implemented in the core, and those defined by placing commands in the
tcl::mathfunc namespace) do not have argument type information;
attempting to retrieve values for them causes a NULL to be stored in
the variable pointed to by procPtr and the variable pointed to by
clientDataPtr will not be modified. The variable pointed to by
numArgsPointer will contain -1, and no argument types will be stored
in the variable pointed to by argTypesPointer.

Tcl_ListMathFuncs returns a Tcl value containing a list of all the
math functions defined in the interpreter whose name matches pattern.
The returned value has a reference count of zero.

KEYWORDS