Tcl_GetIndexFromObj (3)
lookup string in table of keywords
SYNOPSIS
#include <tcl.h>
int
Tcl_GetIndexFromObj(interp, objPtr, tablePtr, msg, flags, indexPtr)
ARGUMENTS
Tcl_Interp **tablePtr
Tcl_Interp *interp in
Interpreter to use for error reporting; if NULL, then no message is
provided on errors.
Tcl_Obj *objPtr in/out
The string value of this object is used to search through tablePtr.
The internal representation is modified to hold the index of the matching
table entry.
char **tablePtr in
An array of null-terminated strings. The end of the array is marked
by a NULL string pointer.
char *msg in
Null-terminated string describing what is being looked up, such as
option. This string is included in error messages.
int flags in
OR-ed combination of bits providing additional information for
operation. The only bit that is currently defined is TCL_EXACT.
int *indexPtr out
The index of the string in tablePtr that matches the value of
objPtr is returned here.
DESCRIPTION
This procedure provides an efficient way for looking up keywords,
switch names, option names, and similar things where the value of
an object must be one of a predefined set of values.
ObjPtr is compared against each of
the strings in tablePtr to find a match. A match occurs if
objPtr's string value is identical to one of the strings in
tablePtr, or if it is a unique abbreviation
for exactly one of the strings in tablePtr and the
TCL_EXACT flag was not specified; in either case
the index of the matching entry is stored at *indexPtr
and TCL_OK is returned.
If there is no matching entry,
TCL_ERROR is returned and an error message is left in interp's
result if interp isn't NULL. Msg is included in the
error message to indicate what was being looked up. For example,
if msg is option the error message will have a form like
bad option "firt": must be first, second, or third.
If Tcl_GetIndexFromObj completes successfully it modifies the
internal representation of objPtr to hold the address of
the table and the index of the matching entry. If Tcl_GetIndexFromObj
is invoked again with the same objPtr and tablePtr
arguments (e.g. during a reinvocation of a Tcl command), it returns
the matching index immediately without having to redo the lookup
operation. Note: Tcl_GetIndexFromObj assumes that the entries
in tablePtr are static: they must not change between invocations.
SEE ALSO
KEYWORDS
index, object, table lookup
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