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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.
SEE ALSO
expr(n), info(n), Tcl_CreateObjCommand(3), Tcl_Free(3),
Tcl_NewListObj(3)
KEYWORDS
expression, mathematical function
Tcl 8.4 Tcl_CreateMathFunc(3)