Tcl_GetAssocData(3)

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NAME

       Tcl_GetAssocData,  Tcl_SetAssocData, Tcl_DeleteAssocData - manage asso-
       ciations of string keys and user specified data with Tcl  interpreters.

SYNOPSIS

       #include <tcl.h>

       ClientData
       Tcl_GetAssocData(interp, key, delProcPtr)

       Tcl_SetAssocData(interp, key, delProc, clientData)

       Tcl_DeleteAssocData(interp, key)

ARGUMENTS

       Tcl_Interp             *interp       (in)      Interpreter  in which to
                                                      execute  the   specified
                                                      command.                 |

       CONST                                                                   |
       char             *key          (in)                               |     |
                                                      Key for association with
                                                      which  to  store data or
                                                      from which to delete  or
                                                      retrieve   data.   Typi-
                                                      cally the module  prefix
                                                      for a package.

       Tcl_InterpDeleteProc   *delProc      (in)      Procedure  to  call when
                                                      interp is deleted.

       Tcl_InterpDeleteProc   **delProcPtr  (in)      Pointer to  location  in
                                                      which  to  store address
                                                      of current deletion pro-
                                                      cedure  for association.
                                                      Ignored if NULL.

       ClientData             clientData    (in)      Arbitrary one-word value
                                                      associated    with   the
                                                      given key in this inter-
                                                      preter.   This  data  is
                                                      owned by the caller.
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DESCRIPTION

       These procedures allow extensions to associate their own  data  with  a
       Tcl  interpreter.   An  association consists of a string key, typically
       the name of the extension, and a one-word value, which is  typically  a
       pointer  to  a  data  structure holding data specific to the extension.
       Tcl makes no interpretation of either the key or the value for an asso-
       ciation.

       Storage  management  is  facilitated by storing with each association a
       procedure to call when the interpreter is deleted. This  procedure  can
       dispose of the storage occupied by the client's data in any way it sees
       fit.

       Tcl_SetAssocData creates an association between a string key and a user
       specified datum in the given interpreter.  If there is already an asso-
       ciation with the given key, Tcl_SetAssocData overwrites it with the new
       information.   It  is  up  to callers to organize their use of names to
       avoid conflicts, for example, by using package names as the  keys.   If
       the  deleteProc argument is non-NULL it specifies the address of a pro-
       cedure to invoke if the interpreter is deleted before  the  association
       is deleted.  DeleteProc should have arguments and result that match the
       type Tcl_InterpDeleteProc:
              typedef void Tcl_InterpDeleteProc(
                ClientData clientData,
                Tcl_Interp *interp);
       When deleteProc is invoked the clientData and interp arguments will  be
       the  same  as  the  corresponding arguments passed to Tcl_SetAssocData.
       The deletion procedure will  not  be  invoked  if  the  association  is
       deleted before the interpreter is deleted.

       Tcl_GetAssocData  returns  the datum stored in the association with the
       specified key in the given interpreter, and if the delProcPtr field  is
       non-NULL,  the  address  indicated by it gets the address of the delete
       procedure stored with this association.  If  no  association  with  the
       specified  key exists in the given interpreter Tcl_GetAssocData returns
       NULL.

       Tcl_DeleteAssocData deletes an association with a specified key in  the
       given interpreter.  Then it calls the deletion procedure.

KEYWORDS

       association, data, deletion procedure, interpreter, key

Tcl                                   7.5                  Tcl_SetAssocData(3)