Tcl_Ensemble(3) Tcl Library Procedures Tcl_Ensemble(3)
Tcl_CreateEnsemble, Tcl_FindEnsemble, Tcl_GetEnsembleFlags, Tcl_GetEnsembleMappingDict,
Tcl_GetEnsembleNamespace, Tcl_GetEnsembleUnknownHandler, Tcl_GetEnsembleSubcommandList,
Tcl_IsEnsemble, Tcl_SetEnsembleFlags, Tcl_SetEnsembleMappingDict, Tcl_SetEnsembleSubcom-
mandList, Tcl_SetEnsembleUnknownHandler - manipulate ensemble commands
Tcl_CreateEnsemble(interp, name, namespacePtr, ensFlags)
Tcl_FindEnsemble(interp, cmdNameObj, flags)
Tcl_GetEnsembleFlags(interp, token, ensFlagsPtr)
Tcl_SetEnsembleFlags(interp, token, ensFlags)
Tcl_GetEnsembleMappingDict(interp, token, dictObjPtr)
Tcl_SetEnsembleMappingDict(interp, token, dictObj)
Tcl_GetEnsembleSubcommandList(interp, token, listObjPtr)
Tcl_SetEnsembleSubcommandList(interp, token, listObj)
Tcl_GetEnsembleUnknownHandler(interp, token, listObjPtr)
Tcl_SetEnsembleUnknownHandler(interp, token, listObj)
Tcl_GetEnsembleNamespace(interp, token, namespacePtrPtr)
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
const char *name (in) The name of the ensemble command to be cre-
Tcl_Namespace *namespacePtr (in) The namespace to which the ensemble command
is to be bound, or NULL for the current
int ensFlags (in) An ORed set of flag bits describing the
basic configuration of the ensemble. Cur-
rently only one bit has meaning, TCL_ENSEM-
BLE_PREFIX, which is present when the ensem-
ble 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
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 han-
dler 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.
An ensemble is a command, bound to some namespace, which consists of a collection of sub-
commands 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 inter-
preter to work within, the name of the ensemble to create, the namespace within the inter-
preter 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.
Every ensemble has four read-write properties and a read-only property. The properties
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 sub-
commands are permitted to be resolved to implementations as well as exact matches.
The flags may be read and written using Tcl_GetEnsembleFlags and Tcl_SetEnsemble-
Flags 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 ensem-
ble 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 names-
pace. 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 ensem-
ble) and the dictionary obtained from Tcl_GetEnsembleMappingDict should always be
treated as immutable even if it is unshared. All command names in prefixes set via
Tcl_SetEnsembleMappingDict must be fully qualified.
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
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 - gener-
ate a suitable error message - will be used when an unknown subcommand is encoun-
tered. 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).
Tcl 8.5 Tcl_Ensemble(3)