focal (3) Tcl_CreateSlave.3tcl.gz
NAME
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
SYNOPSIS
#include <tcl.h>
int
Tcl_IsSafe(interp)
int
Tcl_MakeSafe(interp)
Tcl_Interp *
Tcl_CreateSlave(interp, slaveName, isSafe)
Tcl_Interp *
Tcl_GetSlave(interp, slaveName)
Tcl_Interp *
Tcl_GetMaster(interp)
int
Tcl_GetInterpPath(askingInterp, slaveInterp)
int
Tcl_CreateAlias(slaveInterp, slaveCmd, targetInterp, targetCmd,
argc, argv)
int
Tcl_CreateAliasObj(slaveInterp, slaveCmd, targetInterp, targetCmd,
objc, objv)
int
Tcl_GetAlias(interp, slaveCmd, targetInterpPtr, targetCmdPtr,
argcPtr, argvPtr)
int
Tcl_GetAliasObj(interp, slaveCmd, targetInterpPtr, targetCmdPtr,
objcPtr, objvPtr)
int
Tcl_ExposeCommand(interp, hiddenCmdName, cmdName)
int
Tcl_HideCommand(interp, cmdName, hiddenCmdName)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter in which to execute the specified command.
const char *slaveName (in) Name of slave interpreter to create or manipulate.
int isSafe (in) If non-zero, a “safe” slave that is suitable for
running untrusted code is created, otherwise a trusted
slave is created.
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 targetInterp.
int argc (in) Count of additional arguments to pass to the alias
command.
const char *const *argv (in) Vector of strings, the additional arguments to pass to
the alias command. This storage is owned by the
caller.
int objc (in) Count of additional value arguments to pass to the
aliased command.
Tcl_Obj **objv (in) Vector of Tcl_Obj structures, the additional value
arguments to pass to the aliased 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 command 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 alias.
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 function.
int *objcPtr (out) Pointer to location to store count of additional value
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 arguments to pass to an
alias command. The location is in storage owned by the
caller, the vector of Tcl_Obj structures is owned by
the called function.
const char *cmdName (in) Name of an exposed command to hide or create.
const char *hiddenCmdName (in) Name under which a hidden command is stored and with
which it can be exposed or invoked.
________________________________________________________________________________________________________________
DESCRIPTION
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 returned.
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 master (it is a
top-level interpreter) then NULL is returned.
Tcl_GetInterpPath sets the result field in askingInterp to the relative path between askingInterp 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 a 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 invocation 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 value 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 values 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 value 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 succeed.
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 message in the value 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 value 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 operation 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(3tcl).
SEE ALSO
interp
KEYWORDS
alias, command, exposed commands, hidden commands, interpreter, invoke, master, slave