Tcl_Ensemble(3) Tcl Library Procedures Tcl_Ensemble(3)
NAME
Tcl_CreateEnsemble, Tcl_FindEnsemble, Tcl_GetEnsembleFlags,
Tcl_GetEnsembleMappingDict, Tcl_GetEnsembleNamespace, Tcl_GetEnsemble-
UnknownHandler, Tcl_GetEnsembleSubcommandList, Tcl_IsEnsemble,
Tcl_SetEnsembleFlags, Tcl_SetEnsembleMappingDict, Tcl_SetEnsembleSub-
commandList, Tcl_SetEnsembleUnknownHandler - manipulate ensemble com-
mands
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
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. The name of the ensemble command to be cre-
ated. The namespace to which the ensemble command is to be bound, or
NULL for the current namespace. 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 com-
mand should also match unambiguous prefixes of subcommands. A value
holding the name of the ensemble command to look up. An ORed set of
flag bits controlling the behavior of Tcl_FindEnsemble. Currently only
TCL_LEAVE_ERR_MSG is supported. A normal command token that refers to
an ensemble command, or which you wish to use for testing as an ensem-
ble command in Tcl_IsEnsemble. Pointer to a variable into which to
write the current ensemble flag bits; currently only the bit TCL_ENSEM-
BLE_PREFIX is defined. 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. Pointer to a vari-
able into which to write the current ensemble mapping dictionary. 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. Pointer to a
variable into which to write the current defiend list of subcommands or
the current unknown handler prefix. 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 argu-
ments: the interpreter to work within, the name of the ensemble to cre-
ate, 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 descibed 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 cmd-
NameObj) does not refer to an ensemble command, the result of the func-
tion 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_SetEnsembleMap-
pingDict 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 dic-
tionary (see above) or (if that is also NULL) from the set of
commands exported by the bound namespace. May be read and writ-
ten using Tcl_GetEnsembleSubcommandList and Tcl_SetEnsembleSub-
commandList 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_GetEnsem-
bleSubcommandList should alays 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 cur-
rent 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_GetEnsembleUn-
knownHandler 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(n), Tcl_DeleteCommandFromToken(3)
Tcl 8.5 Tcl_Ensemble(3)
Ensemble 8.5.4 - Generated Mon Aug 18 07:32:44 CDT 2008