Tcl_CreateSlave(3) Tcl Library Procedures Tcl_CreateSlave(3)
Tcl_IsSafe, Tcl_MakeSafe, Tcl_CreateSlave, Tcl_GetSlave, Tcl_GetMaster, Tcl_GetInterpPath,
Tcl_CreateAlias, Tcl_CreateAliasObj, Tcl_GetAlias, Tcl_GetAliasObj, Tcl_ExposeCommand,
Tcl_HideCommand - manage multiple Tcl interpreters, aliases and hidden commands
Tcl_CreateSlave(interp, slaveName, isSafe)
Tcl_CreateAlias(slaveInterp, slaveCmd, targetInterp, targetCmd,
Tcl_CreateAliasObj(slaveInterp, slaveCmd, targetInterp, targetCmd,
Tcl_GetAlias(interp, slaveCmd, targetInterpPtr, targetCmdPtr,
Tcl_GetAliasObj(interp, slaveCmd, targetInterpPtr, targetCmdPtr,
Tcl_ExposeCommand(interp, hiddenCmdName, cmdName)
Tcl_HideCommand(interp, cmdName, hiddenCmdName)
Tcl_Interp *interp (in) Interpreter in which to execute the
const char *slaveName (in) Name of slave interpreter to create or
int isSafe (in) If non-zero, a "safe" slave that is
suitable for running untrusted code is
created, otherwise a trusted slave is
Tcl_Interp *slaveInterp (in) Interpreter to use for creating the
source command for an alias (see below).
const char *slaveCmd (in) Name of source command for alias.
Tcl_Interp *targetInterp (in) Interpreter that contains the target
command for an alias.
const char *targetCmd (in) Name of target command for alias in tar-
int argc (in) Count of additional arguments to pass to
the alias command.
const char *const *argv (in) Vector of strings, the additional argu-
ments to pass to the alias command.
This storage is owned by the caller.
int objc (in) Count of additional object arguments to
pass to the alias object command.
Tcl_Obj **objv (in) Vector of Tcl_Obj structures, the addi-
tional object arguments to pass to the
alias object command. This storage is
owned by the caller.
Tcl_Interp **targetInterpPtr (in) Pointer to location to store the address
of the interpreter where a target com-
mand is defined for an alias.
const char **targetCmdPtr (out) Pointer to location to store the address
of the name of the target command for an
int *argcPtr (out) Pointer to location to store count of
additional arguments to be passed to the
alias. The location is in storage owned
by the caller.
const char ***argvPtr (out) Pointer to location to store a vector of
strings, the additional arguments to
pass to an alias. The location is in
storage owned by the caller, the vector
of strings is owned by the called func-
int *objcPtr (out) Pointer to location to store count of
additional object arguments to be passed
to the alias. The location is in storage
owned by the caller.
Tcl_Obj ***objvPtr (out) Pointer to location to store a vector of
Tcl_Obj structures, the additional argu-
ments to pass to an object alias com-
mand. The location is in storage owned
by the caller, the vector of Tcl_Obj
structures is owned by the called func-
const char *cmdName (in) Name of an exposed command to hide or
const char *hiddenCmdName (in) Name under which a hidden command is
stored and with which it can be exposed
These procedures are intended for access to the multiple interpreter facility from inside
C programs. They enable managing multiple interpreters in a hierarchical relationship, and
the management of aliases, commands that when invoked in one interpreter execute a command
in another interpreter. The return value for those procedures that return an int is either
TCL_OK or TCL_ERROR. If TCL_ERROR is returned then the result field of the interpreter
contains an error message.
Tcl_CreateSlave creates a new interpreter as a slave of interp. It also creates a slave
command named slaveName in interp which allows interp to manipulate the new slave. If
isSafe is zero, the command creates a trusted slave in which Tcl code has access to all
the Tcl commands. If it is 1, the command creates a "safe" slave in which Tcl code has
access only to set of Tcl commands defined as "Safe Tcl"; see the manual entry for the Tcl
interp command for details. If the creation of the new slave interpreter failed, NULL is
Tcl_IsSafe returns 1 if interp is "safe" (was created with the TCL_SAFE_INTERPRETER flag
specified), 0 otherwise.
Tcl_MakeSafe marks interp as "safe", so that future calls to Tcl_IsSafe will return 1. It
also removes all known potentially-unsafe core functionality (both commands and variables)
from interp. However, it cannot know what parts of an extension or application are safe
and does not make any attempt to remove those parts, so safety is not guaranteed after
calling Tcl_MakeSafe. Callers will want to take care with their use of Tcl_MakeSafe to
avoid false claims of safety. For many situations, Tcl_CreateSlave may be a better
choice, since it creates interpreters in a known-safe state.
Tcl_GetSlave returns a pointer to a slave interpreter of interp. The slave interpreter is
identified by slaveName. If no such slave interpreter exists, NULL is returned.
Tcl_GetMaster returns a pointer to the master interpreter of interp. If interp has no mas-
ter (it is a top-level interpreter) then NULL is returned.
Tcl_GetInterpPath sets the result field in askingInterp to the relative path between ask-
ingInterp and slaveInterp; slaveInterp must be a slave of askingInterp. If the computation
of the relative path succeeds, TCL_OK is returned, else TCL_ERROR is returned and the
result field in askingInterp contains the error message.
Tcl_CreateAlias creates an object command named slaveCmd in slaveInterp that when invoked,
will cause the command targetCmd to be invoked in targetInterp. The arguments specified by
the strings contained in argv are always prepended to any arguments supplied in the invo-
cation of slaveCmd and passed to targetCmd. This operation returns TCL_OK if it succeeds,
or TCL_ERROR if it fails; in that case, an error message is left in the object result of
slaveInterp. Note that there are no restrictions on the ancestry relationship (as created
by Tcl_CreateSlave) between slaveInterp and targetInterp. Any two interpreters can be
used, without any restrictions on how they are related.
Tcl_CreateAliasObj is similar to Tcl_CreateAlias except that it takes a vector of objects
to pass as additional arguments instead of a vector of strings.
Tcl_GetAlias returns information about an alias aliasName in interp. Any of the result
fields can be NULL, in which case the corresponding datum is not returned. If a result
field is non-NULL, the address indicated is set to the corresponding datum. For example,
if targetNamePtr is non-NULL it is set to a pointer to the string containing the name of
the target command.
Tcl_GetAliasObj is similar to Tcl_GetAlias except that it returns a pointer to a vector of
Tcl_Obj structures instead of a vector of strings.
Tcl_ExposeCommand moves the command named hiddenCmdName from the set of hidden commands to
the set of exposed commands, putting it under the name cmdName. HiddenCmdName must be the
name of an existing hidden command, or the operation will return TCL_ERROR and leave an
error message in the result field in interp. If an exposed command named cmdName already
exists, the operation returns TCL_ERROR and leaves an error message in the object result
of interp. If the operation succeeds, it returns TCL_OK. After executing this command,
attempts to use cmdName in a call to Tcl_Eval or with the Tcl eval command will again suc-
Tcl_HideCommand moves the command named cmdName from the set of exposed commands to the
set of hidden commands, under the name hiddenCmdName. CmdName must be the name of an
existing exposed command, or the operation will return TCL_ERROR and leave an error mes-
sage in the object result of interp. Currently both cmdName and hiddenCmdName must not
contain namespace qualifiers, or the operation will return TCL_ERROR and leave an error
message in the object result of interp. The CmdName will be looked up in the global
namespace, and not relative to the current namespace, even if the current namespace is not
the global one. If a hidden command whose name is hiddenCmdName already exists, the oper-
ation also returns TCL_ERROR and the result field in interp contains an error message. If
the operation succeeds, it returns TCL_OK. After executing this command, attempts to use
cmdName in a call to Tcl_Eval or with the Tcl eval command will fail.
For a description of the Tcl interface to multiple interpreters, see interp(n).
alias, command, exposed commands, hidden commands, interpreter, invoke, master, slave
Tcl 7.6 Tcl_CreateSlave(3)