Tcl_GetCommandFromObj man page on QNX

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Tcl_CreateObjCommand(3)	    Tcl Library Procedures     Tcl_CreateObjCommand(3)


       Tcl_CreateObjCommand,   Tcl_DeleteCommand,  Tcl_DeleteCommandFromToken,
       Tcl_GetCommandInfo,  Tcl_GetCommandInfoFromToken,   Tcl_SetCommandInfo,
       Tcl_SetCommandInfoFromToken,   Tcl_GetCommandName,  Tcl_GetCommandFull‐
       Name, Tcl_GetCommandFromObj - implement new commands in C

       #include <tcl.h>

       Tcl_CreateObjCommand(interp, cmdName, proc, clientData, deleteProc)

       Tcl_DeleteCommand(interp, cmdName)

       Tcl_DeleteCommandFromToken(interp, token)

       Tcl_GetCommandInfo(interp, cmdName, infoPtr)

       Tcl_SetCommandInfo(interp, cmdName, infoPtr)

       int								       │
       Tcl_GetCommandInfoFromToken(token, infoPtr)			       │

       int								       │
       Tcl_SetCommandInfoFromToken(token, infoPtr)			       │

       CONST char *							       │
       Tcl_GetCommandName(interp, token)

       Tcl_GetCommandFullName(interp, token, objPtr)

       Tcl_GetCommandFromObj(interp, objPtr)

       Tcl_Interp	*interp	      (in)	Interpreter in which to create
						a new command or that contains
						a command.		       │

       char		*cmdName      (in)				       │
						Name of command.

       Tcl_ObjCmdProc	*proc	      (in)	Implementation of the new com‐
						mand:	proc  will  be	called
						whenever cmdName is invoked as
						a command.

       ClientData	clientData    (in)	Arbitrary  one-word  value  to
						pass to proc and deleteProc.

       Tcl_CmdDeleteProc	      *deleteProc(in)
						Procedure to call before  cmd‐
						Name   is   deleted  from  the
						interpreter; allows  for  com‐
						mand-specific	 cleanup.   If
						NULL,  then  no	 procedure  is
						called	before	the command is

       Tcl_Command	token	      (in)	Token for command, returned by
						previous call to Tcl_CreateOb‐
						jCommand.   The	 command  must
						not have been deleted.

       Tcl_CmdInfo	*infoPtr      (in/out)	Pointer	 to structure contain‐
						ing various information	 about
						a Tcl command.

       Tcl_Obj		*objPtr	      (in)	Object	containing the name of
						a Tcl command.

       Tcl_CreateObjCommand defines a new command in interp and associates  it
       with procedure proc such that whenever name is invoked as a Tcl command
       (e.g., via a call to Tcl_EvalObjEx) the Tcl interpreter will call  proc
       to process the command.

       Tcl_CreateObjCommand  deletes any existing command name already associ‐
       ated with the interpreter (however see below for an exception where the
       existing	 command is not deleted).  It returns a token that may be used
       to refer to the command in subsequent calls to Tcl_GetCommandName.   If
       name contains any :: namespace qualifiers, then the command is added to
       the specified namespace; otherwise the command is added to  the	global
       namespace.   If	Tcl_CreateObjCommand is called for an interpreter that
       is in the process of being deleted, then it does not create a new  com‐
       mand  and  it returns NULL.  proc should have arguments and result that
       match the type Tcl_ObjCmdProc:
	      typedef int Tcl_ObjCmdProc(
		ClientData clientData,
		Tcl_Interp *interp,
		int objc,
		Tcl_Obj *CONST objv[]);					       │
       When proc is invoked, the clientData  and  interp  parameters  will  be │
       copies  of  the clientData and interp arguments given to Tcl_CreateObj‐ │
       Command.	 Typically, clientData points to an application-specific  data │
       structure  that	describes  what	 to  do	 when the command procedure is │
       invoked. Objc and objv describe the arguments to the command, objc giv‐ │
       ing  the	 number	 of  argument objects (including the command name) and │
       objv giving the values of the arguments.	 The objv array	 will  contain │
       objc  values, pointing to the argument objects.	Unlike argv[argv] used │
       in a string-based command procedure, objv[objc] will not contain NULL.  │

       Additionally, when proc is invoked, it must not modify the contents  of │
       the  objv  array	 by assigning new pointer values to any element of the │
       array (for example, objv[2] = NULL) because this will cause  memory  to │
       be lost and the runtime stack to be corrupted.  The CONST in the decla‐ │
       ration of objv will cause ANSI-compliant compilers to report  any  such │
       attempted  assignment as an error.  However, it is acceptable to modify │
       the internal representation of any  individual  object  argument.   For │
       instance,  the user may call Tcl_GetIntFromObj on objv[2] to obtain the │
       integer representation of that object; that call may change the type of │
       the  object  that  objv[2] points at, but will not change where objv[2] │

       proc must return an integer code	 that  is  either  TCL_OK,  TCL_ERROR,
       TCL_RETURN,  TCL_BREAK, or TCL_CONTINUE.	 See the Tcl overview man page
       for details on what these codes mean.  Most normal commands  will  only
       return  TCL_OK  or  TCL_ERROR.	In addition, if proc needs to return a
       non-empty result, it can call Tcl_SetObjResult to set the interpreter's
       result.	 In  the case of a TCL_OK return code this gives the result of
       the command, and in the case of TCL_ERROR this gives an error  message.
       Before  invoking	 a command procedure, Tcl_EvalObjEx sets interpreter's
       result to point to an object representing an empty  string,  so	simple
       commands can return an empty result by doing nothing at all.

       The  contents of the objv array belong to Tcl and are not guaranteed to
       persist once proc returns: proc should not modify them.	Call Tcl_SetO‐
       bjResult if you want to return something from the objv array.

       Ordinarily,  Tcl_CreateObjCommand  deletes  any	existing  command name
       already associated with the interpreter.	 However, if the existing com‐
       mand was created by a previous call to Tcl_CreateCommand, Tcl_CreateOb‐
       jCommand does not delete the command but instead arranges for  the  Tcl
       interpreter  to	call  the  Tcl_ObjCmdProc proc in the future.  The old
       string-based Tcl_CmdProc associated with the command  is	 retained  and
       its  address  can  be  obtained by subsequent Tcl_GetCommandInfo calls.
       This is done for backwards compatibility.

       DeleteProc will be invoked when (if) name is deleted.  This  can	 occur
       through	a  call	 to  Tcl_DeleteCommand, Tcl_DeleteCommandFromToken, or
       Tcl_DeleteInterp, or by replacing name in another call to Tcl_CreateOb‐
       jCommand.   DeleteProc  is  invoked  before the command is deleted, and
       gives the application an opportunity to release any structures  associ‐
       ated  with  the	command.   DeleteProc should have arguments and result
       that match the type Tcl_CmdDeleteProc:
	      typedef void Tcl_CmdDeleteProc(ClientData clientData);
       The clientData argument will be the same	 as  the  clientData  argument
       passed to Tcl_CreateObjCommand.

       Tcl_DeleteCommand  deletes  a command from a command interpreter.  Once
       the call completes, attempts to invoke cmdName in interp will result in
       errors.	  If   cmdName	isn't  bound  as  a  command  in  interp  then
       Tcl_DeleteCommand does nothing and returns -1;  otherwise it returns 0.
       There  are no restrictions on cmdName:  it may refer to a built-in com‐
       mand, an application-specific command, or a  Tcl	 procedure.   If  name
       contains	 any  :: namespace qualifiers, the command is deleted from the
       specified namespace.

       Given a token returned by Tcl_CreateObjCommand,	Tcl_DeleteCommandFrom‐
       Token deletes the command from a command interpreter.  It will delete a
       command even if that command has been  renamed.	 Once  the  call  com‐
       pletes, attempts to invoke the command in interp will result in errors.
       If the command corresponding to token has  already  been	 deleted  from
       interp then Tcl_DeleteCommand does nothing and returns -1; otherwise it
       returns 0.

       Tcl_GetCommandInfo checks to see whether its cmdName argument exists as
       a  command  in  interp.	cmdName may include :: namespace qualifiers to
       identify a command in a particular namespace.  If the  command  is  not
       found,  then  it	 returns 0.  Otherwise it places information about the
       command in the Tcl_CmdInfo structure pointed to by infoPtr and  returns
       1.  A Tcl_CmdInfo structure has the following fields:
	      typedef struct Tcl_CmdInfo {
		  int isNativeObjectProc;
		  Tcl_ObjCmdProc *objProc;
		  ClientData objClientData;
		  Tcl_CmdProc *proc;
		  ClientData clientData;
		  Tcl_CmdDeleteProc *deleteProc;
		  ClientData deleteData;
		  Tcl_Namespace *namespacePtr;
	      } Tcl_CmdInfo;
       The  isNativeObjectProc	field  has the value 1 if Tcl_CreateObjCommand
       was called to register the command; it is 0 if  only  Tcl_CreateCommand
       was  called.   It allows a program to determine whether it is faster to
       call objProc or proc: objProc is normally faster if  isNativeObjectProc
       has  the	 value	1.  The fields objProc and objClientData have the same
       meaning as the proc and clientData arguments  to	 Tcl_CreateObjCommand;
       they hold information about the object-based command procedure that the
       Tcl interpreter calls to implement the command.	The  fields  proc  and
       clientData  hold	 information  about the string-based command procedure
       that implements the command.  If Tcl_CreateCommand was called for  this
       command,	 this is the procedure passed to it; otherwise, this is a com‐
       patibility procedure registered	by  Tcl_CreateObjCommand  that	simply
       calls  the command's object-based procedure after converting its string
       arguments to Tcl objects.  The field deleteData is the ClientData value
       to  pass	 to deleteProc;	 it is normally the same as clientData but may
       be set independently using the Tcl_SetCommandInfo procedure.  The field
       namespacePtr  holds  a  pointer	to the Tcl_Namespace that contains the

       Tcl_GetCommandInfoFromToken is identical to  Tcl_GetCommandInfo	except
       that  it	 uses  a  command  token returned from Tcl_CreateObjCommand in
       place of the command name.  If the token parameter is NULL, it  returns
       0;  otherwise,  it  returns  1 and fills in the structure designated by

       Tcl_SetCommandInfo is used to modify the procedures and ClientData val‐
       ues  associated	with a command.	 Its cmdName argument is the name of a
       command in interp.  cmdName may	include	 ::  namespace	qualifiers  to
       identify a command in a particular namespace.  If this command does not
       exist then Tcl_SetCommandInfo returns  0.   Otherwise,  it  copies  the
       information  from  *infoPtr to Tcl's internal structure for the command
       and returns 1.

       Tcl_SetCommandInfoFromToken is identical to  Tcl_SetCommandInfo	except
       that  it	 takes	a  command  token  as returned by Tcl_CreateObjCommand
       instead of the command name.   If  the  token  parameter	 is  NULL,  it
       returns 0.  Otherwise, it copies the information from *infoPtr to Tcl's
       internal structure for the command and returns 1.

       Note that Tcl_SetCommandInfo and Tcl_SetCommandInfoFromToken both allow
       the ClientData for a command's deletion procedure to be given a differ‐
       ent value than the ClientData for its command procedure.

       Note that neither  Tcl_SetCommandInfo  nor  Tcl_SetCommandInfoFromToken
       will  change  a	command's  namespace.  Use Tcl_Eval to call the rename
       command to do that.

       Tcl_GetCommandName provides a mechanism for tracking commands that have
       been  renamed.  Given a token returned by Tcl_CreateObjCommand when the
       command was created, Tcl_GetCommandName returns the string name of  the
       command.	  If  the  command has been renamed since it was created, then
       Tcl_GetCommandName returns  the	current	 name.	 This  name  does  not
       include	any  ::	 namespace  qualifiers.	  The command corresponding to
       token must not have been deleted.  The string returned  by  Tcl_GetCom‐
       mandName	 is  in	 dynamic memory owned by Tcl and is only guaranteed to
       retain its value as long as  the	 command  isn't	 deleted  or  renamed;
       callers should copy the string if they need to keep it for a long time.

       Tcl_GetCommandFullName  produces	 the fully-qualified name of a command
       from a command token.  The name, including all namespace	 prefixes,  is
       appended to the object specified by objPtr.

       Tcl_GetCommandFromObj  returns a token for the command specified by the
       name in a Tcl_Obj.  The command name is resolved relative to  the  cur‐
       rent namespace.	Returns NULL if the command is not found.

       Tcl_CreateCommand, Tcl_ResetResult, Tcl_SetObjResult

       bind, command, create, delete, namespace, object

Tcl				      8.0	       Tcl_CreateObjCommand(3)
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