NAME¶
Tcl_CreateEnsemble, Tcl_FindEnsemble, Tcl_GetEnsembleFlags,
Tcl_GetEnsembleMappingDict, Tcl_GetEnsembleNamespace,
Tcl_GetEnsembleUnknownHandler, Tcl_GetEnsembleSubcommandList, Tcl_IsEnsemble,
Tcl_SetEnsembleFlags, Tcl_SetEnsembleMappingDict,
Tcl_SetEnsembleSubcommandList, Tcl_SetEnsembleUnknownHandler - manipulate
ensemble commands
SYNOPSIS¶
#include <tcl.h>
Tcl_Command
Tcl_CreateEnsemble(interp, name, namespacePtr, ensFlags)
Tcl_Command
Tcl_FindEnsemble(interp, cmdNameObj, flags)
int
Tcl_IsEnsemble(token)
int
Tcl_GetEnsembleFlags(interp, token, ensFlagsPtr)
int
Tcl_SetEnsembleFlags(interp, token, ensFlags)
int
Tcl_GetEnsembleMappingDict(interp, token, dictObjPtr)
int
Tcl_SetEnsembleMappingDict(interp, token, dictObj)
int
Tcl_GetEnsembleSubcommandList(interp, token, listObjPtr)
int
Tcl_SetEnsembleSubcommandList(interp, token, listObj)
int
Tcl_GetEnsembleUnknownHandler(interp, token, listObjPtr)
int
Tcl_SetEnsembleUnknownHandler(interp, token, listObj)
int
Tcl_GetEnsembleNamespace(interp, token, namespacePtrPtr)
ARGUMENTS¶
- Tcl_Interp *interp (in/out)
- The interpreter in which the ensemble is to be created or
found. Also where error result messages are written. The functions whose
names start with Tcl_GetEnsemble may have a NULL for the
interp, but all other functions must not.
- const char *name (in)
- The name of the ensemble command to be created.
- Tcl_Namespace *namespacePtr (in)
- The namespace to which the ensemble command is to be bound,
or NULL for the current namespace.
- int ensFlags (in)
- An ORed set of flag bits describing the basic configuration
of the ensemble. Currently only one bit has meaning, TCL_ENSEMBLE_PREFIX,
which is present when the ensemble command should also match unambiguous
prefixes of subcommands.
- Tcl_Obj *cmdNameObj (in)
- A value holding the name of the ensemble command to look
up.
- int flags (in)
- An ORed set of flag bits controlling the behavior of
Tcl_FindEnsemble. Currently only TCL_LEAVE_ERR_MSG is
supported.
- Tcl_Command token (in)
- A normal command token that refers to an ensemble command,
or which you wish to use for testing as an ensemble command in
Tcl_IsEnsemble.
- int *ensFlagsPtr (out)
- Pointer to a variable into which to write the current
ensemble flag bits; currently only the bit TCL_ENSEMBLE_PREFIX is
defined.
- Tcl_Obj *dictObj (in)
- A dictionary value to use for the subcommand to
implementation command prefix mapping dictionary in the ensemble. May be
NULL if the mapping dictionary is to be removed.
- Tcl_Obj **dictObjPtr (out)
- Pointer to a variable into which to write the current
ensemble mapping dictionary.
- Tcl_Obj *listObj (in)
- A list value to use for the defined list of subcommands in
the dictionary or the unknown subcommmand handler command prefix. May be
NULL if the subcommand list or unknown handler are to be removed.
- Tcl_Obj **listObjPtr (out)
- Pointer to a variable into which to write the current
defiend list of subcommands or the current unknown handler prefix.
- Tcl_Namespace **namespacePtrPtr (out)
- Pointer to a variable into which to write the handle of the
namespace to which the ensemble is bound.
DESCRIPTION¶
An ensemble is a command, bound to some namespace, which consists of a
collection of subcommands implemented by other Tcl commands. The first
argument to the ensemble command is always interpreted as a selector that
states what subcommand to execute.
Ensembles are created using
Tcl_CreateEnsemble, which takes four
arguments: the interpreter to work within, the name of the ensemble to create,
the namespace within the interpreter to bind the ensemble to, and the default
set of ensemble flags. The result of the function is the command token for the
ensemble, which may be used to further configure the ensemble using the API
described below in
ENSEMBLE PROPERTIES.
Given the name of an ensemble command, the token for that command may be
retrieved using
Tcl_FindEnsemble. If the given command name (in
cmdNameObj) does not refer to an ensemble command, the result of the
function is NULL and (if the TCL_LEAVE_ERR_MSG bit is set in
flags) an
error message is left in the interpreter result.
A command token may be checked to see if it refers to an ensemble using
Tcl_IsEnsemble. This returns 1 if the token refers to an ensemble, or 0
otherwise.
ENSEMBLE PROPERTIES¶
Every ensemble has four read-write properties and a read-only property. The
properties are:
- flags (read-write)
- The set of flags for the ensemble, expressed as a
bit-field. Currently, the only public flag is TCL_ENSEMBLE_PREFIX which is
set when unambiguous prefixes of subcommands are permitted to be resolved
to implementations as well as exact matches. The flags may be read and
written using Tcl_GetEnsembleFlags and Tcl_SetEnsembleFlags
respectively. The result of both of those functions is a Tcl result code
(TCL_OK, or TCL_ERROR if the token does not refer to an ensemble).
- mapping dictionary (read-write)
- A dictionary containing a mapping from subcommand names to
lists of words to use as a command prefix (replacing the first two words
of the command which are the ensemble command itself and the subcommand
name), or NULL if every subcommand is to be mapped to the command with the
same unqualified name in the ensemble's bound namespace. Defaults to NULL.
May be read and written using Tcl_GetEnsembleMappingDict and
Tcl_SetEnsembleMappingDict respectively. The result of both of
those functions is a Tcl result code (TCL_OK, or TCL_ERROR if the token
does not refer to an ensemble) and the dictionary obtained from
Tcl_GetEnsembleMappingDict should always be treated as immutable
even if it is unshared.
- subcommand list (read-write)
- A list of all the subcommand names for the ensemble, or
NULL if this is to be derived from either the keys of the mapping
dictionary (see above) or (if that is also NULL) from the set of commands
exported by the bound namespace. May be read and written using
Tcl_GetEnsembleSubcommandList and
Tcl_SetEnsembleSubcommandList respectively. The result of both of
those functions is a Tcl result code (TCL_OK, or TCL_ERROR if the token
does not refer to an ensemble) and the list obtained from
Tcl_GetEnsembleSubcommandList should always be treated as immutable
even if it is unshared.
- unknown subcommand handler command prefix
(read-write)
- A list of words to prepend on the front of any subcommand
when the subcommand is unknown to the ensemble (according to the current
prefix handling rule); see the namespace ensemble command for more
details. If NULL, the default behavior - generate a suitable error message
- will be used when an unknown subcommand is encountered. May be read and
written using Tcl_GetEnsembleUnknownHandler and
Tcl_SetEnsembleUnknownHandler respectively. The result of both
functions is a Tcl result code (TCL_OK, or TCL_ERROR if the token does not
refer to an ensemble) and the list obtained from
Tcl_GetEnsembleUnknownHandler should always be treated as immutable
even if it is unshared.
- bound namespace (read-only)
- The namespace to which the ensemble is bound; when the
namespace is deleted, so too will the ensemble, and this namespace is also
the namespace whose list of exported commands is used if both the mapping
dictionary and the subcommand list properties are NULL. May be read using
Tcl_GetEnsembleNamespace which returns a Tcl result code (TCL_OK,
or TCL_ERROR if the token does not refer to an ensemble).
SEE ALSO¶
namespace(3tcl), Tcl_DeleteCommandFromToken(3tcl)