path: root/doc/CrtAlias.3

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.TH Tcl_CreateAlias 3 7.6 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_IsSafe, Tcl_MakeSafe, Tcl_CreateChild, Tcl_GetChild, Tcl_GetParent, Tcl_GetInterpPath, Tcl_CreateAlias, Tcl_CreateAliasObj, Tcl_GetAlias, Tcl_GetAliasObj, Tcl_ExposeCommand, Tcl_HideCommand \- manage multiple Tcl interpreters, aliases and hidden commands
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
int
\fBTcl_IsSafe\fR(\fIinterp\fR)
.sp
int
\fBTcl_MakeSafe\fR(\fIinterp\fR)
.sp
Tcl_Interp *
\fBTcl_CreateChild\fR(\fIinterp, name, isSafe\fR)
.sp
Tcl_Interp *
\fBTcl_GetChild\fR(\fIinterp, name\fR)
.sp
Tcl_Interp *
\fBTcl_GetParent\fR(\fIinterp\fR)
.sp
int
\fBTcl_GetInterpPath\fR(\fIinterp, childInterp\fR)
.sp
int
\fBTcl_CreateAlias\fR(\fIchildInterp, childCmd, targetInterp, targetCmd,
                argc, argv\fR)
.sp
int
\fBTcl_CreateAliasObj\fR(\fIchildInterp, childCmd, targetInterp, targetCmd,
                   objc, objv\fR)
.sp
int
\fBTcl_GetAlias\fR(\fIinterp, childCmd, targetInterpPtr, targetCmdPtr,
             argcPtr, argvPtr\fR)
.sp
int
\fBTcl_GetAliasObj\fR(\fIinterp, childCmd, targetInterpPtr, targetCmdPtr,
                objcPtr, objvPtr\fR)
.sp
int
\fBTcl_ExposeCommand\fR(\fIinterp, hiddenCmdName, cmdName\fR)
.sp
int
\fBTcl_HideCommand\fR(\fIinterp, cmdName, hiddenCmdName\fR)
.SH ARGUMENTS
.AS "const char *const" **targetInterpPtr out
.AP Tcl_Interp *interp in
Interpreter in which to execute the specified command.
.AP "const char" *name in
Name of child interpreter to create or manipulate.
.AP int isSafe in
If non-zero, a
.QW safe
child that is suitable for running untrusted code
is created, otherwise a trusted child is created.
.AP Tcl_Interp *childInterp in
Interpreter to use for creating the source command for an alias (see
below).
.AP "const char" *childCmd in
Name of source command for alias.
.AP Tcl_Interp *targetInterp in
Interpreter that contains the target command for an alias.
.AP "const char" *targetCmd in
Name of target command for alias in \fItargetInterp\fR.
.AP int argc in
Count of additional arguments to pass to the alias command.
.AP "const char *const" *argv in
Vector of strings, the additional arguments to pass to the alias command.
This storage is owned by the caller.
.AP int objc in
Count of additional value arguments to pass to the aliased command.
.AP 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.
.AP Tcl_Interp **targetInterpPtr in
Pointer to location to store the address of the interpreter where a target
command is defined for an alias.
.AP "const char" **targetCmdPtr out
Pointer to location to store the address of the name of the target command
for an alias.
.AP 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.
.AP "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.
.AP 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.
.AP 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.
.AP "const char" *cmdName in
Name of an exposed command to hide or create.
.AP "const char" *hiddenCmdName in
Name under which a hidden command is stored and with which it can be
exposed or invoked.
.BE

.SH DESCRIPTION
.PP
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 \fBint\fR
is either \fBTCL_OK\fR or \fBTCL_ERROR\fR. If \fBTCL_ERROR\fR is returned
then the interpreter's result contains an error message.
.PP
\fBTcl_CreateChild\fR creates a new interpreter as a child of \fIinterp\fR.
It also creates a child command named \fIname\fR in \fIinterp\fR which
allows \fIinterp\fR to manipulate the new child.
If \fIisSafe\fR is zero, the command creates a trusted child in which Tcl
code has access to all the Tcl commands.
If it is \fB1\fR, the command creates a
.QW safe
child in which Tcl code has access only to set of Tcl commands defined as
.QW "Safe Tcl" ;
see the manual entry for the Tcl \fBinterp\fR command for details.
If the creation of the new child interpreter failed, \fBNULL\fR is returned.
.PP
\fBTcl_IsSafe\fR returns \fB1\fR if \fIinterp\fR is
.QW safe
(was created with the \fBTCL_SAFE_INTERPRETER\fR flag specified),
\fB0\fR otherwise.
.PP
\fBTcl_MakeSafe\fR marks \fIinterp\fR as
.QW safe ,
so that future
calls to \fBTcl_IsSafe\fR will return 1.  It also removes all known
potentially-unsafe core functionality (both commands and variables)
from \fIinterp\fR.  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 \fBTcl_MakeSafe\fR.
Callers will want to take care with their use of \fBTcl_MakeSafe\fR
to avoid false claims of safety.  For many situations, \fBTcl_CreateChild\fR
may be a better choice, since it creates interpreters in a known-safe state.
.PP
\fBTcl_GetChild\fR returns a pointer to a child interpreter of
\fIinterp\fR. The child interpreter is identified by \fIname\fR.
If no such child interpreter exists, \fBNULL\fR is returned.
.PP
\fBTcl_GetParent\fR returns a pointer to the parent interpreter of
\fIinterp\fR. If \fIinterp\fR has no parent (it is a
top-level interpreter) then \fBNULL\fR is returned.
.PP
\fBTcl_GetInterpPath\fR stores in the result of \fIinterp\fR
the relative path between \fIinterp\fR and \fIchildInterp\fR;
\fIchildInterp\fR must be a child of \fIinterp\fR. If the computation
of the relative path succeeds, \fBTCL_OK\fR is returned, else
\fBTCL_ERROR\fR is returned and an error message is stored as the
result of \fIinterp\fR.
.PP
\fBTcl_CreateAlias\fR creates a command named \fIchildCmd\fR in
\fIchildInterp\fR that when invoked, will cause the command \fItargetCmd\fR
to be invoked in \fItargetInterp\fR. The arguments specified by the strings
contained in \fIargv\fR are always prepended to any arguments supplied in the
invocation of \fIchildCmd\fR and passed to \fItargetCmd\fR.
This operation returns \fBTCL_OK\fR if it succeeds, or \fBTCL_ERROR\fR if
it fails; in that case, an error message is left in the value result
of \fIchildInterp\fR.
Note that there are no restrictions on the ancestry relationship (as
created by \fBTcl_CreateChild\fR) between \fIchildInterp\fR and
\fItargetInterp\fR. Any two interpreters can be used, without any
restrictions on how they are related.
.PP
\fBTcl_CreateAliasObj\fR is similar to \fBTcl_CreateAlias\fR except
that it takes a vector of values to pass as additional arguments instead
of a vector of strings.
.PP
\fBTcl_GetAlias\fR returns information about an alias \fIaliasName\fR
in \fIinterp\fR. Any of the result fields can be \fBNULL\fR, in
which case the corresponding datum is not returned. If a result field is
non\-\fBNULL\fR, the address indicated is set to the corresponding datum.
For example, if \fItargetNamePtr\fR is non\-\fBNULL\fR it is set to a
pointer to the string containing the name of the target command.
.PP
\fBTcl_GetAliasObj\fR is similar to \fBTcl_GetAlias\fR except that it
returns a pointer to a vector of Tcl_Obj structures instead of a vector of
strings.
.PP
\fBTcl_ExposeCommand\fR moves the command named \fIhiddenCmdName\fR from
the set of hidden commands to the set of exposed commands, putting
it under the name
\fIcmdName\fR.
\fIHiddenCmdName\fR must be the name of an existing hidden
command, or the operation will return \fBTCL_ERROR\fR and
leave an error message as the result of \fIinterp\fR.
If an exposed command named \fIcmdName\fR already exists,
the operation returns \fBTCL_ERROR\fR and leaves an error message as
the result of \fIinterp\fR.
If the operation succeeds, it returns \fBTCL_OK\fR.
After executing this command, attempts to use \fIcmdName\fR in any
script evaluation mechanism will again succeed.
.PP
\fBTcl_HideCommand\fR moves the command named \fIcmdName\fR from the set of
exposed commands to the set of hidden commands, under the name
\fIhiddenCmdName\fR.
\fICmdName\fR must be the name of an existing exposed
command, or the operation will return \fBTCL_ERROR\fR and leave an error
message as the result of \fIinterp\fR.
Currently both \fIcmdName\fR and \fIhiddenCmdName\fR must not contain
namespace qualifiers, or the operation will return \fBTCL_ERROR\fR and
leave an error message as the result of \fIinterp\fR.
The \fICmdName\fR 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 \fIhiddenCmdName\fR already
exists, the operation also returns \fBTCL_ERROR\fR and an error
message is left as the result of \fIinterp\fR.
If the operation succeeds, it returns \fBTCL_OK\fR.
After executing this command, attempts to use \fIcmdName\fR in
any script evaluation mechanism will fail.
.PP
For a description of the Tcl interface to multiple interpreters, see
\fIinterp(n)\fR.
.SH "SEE ALSO"
interp

.SH KEYWORDS
alias, command, exposed commands, hidden commands, interpreter, invoke,
parent, child