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Tcl_SaveInterpState(3tcl) Tcl Library Procedures Tcl_SaveInterpState(3tcl) 





NAME


Tcl_SaveInterpState, Tcl_RestoreInterpState,
    Tcl_DiscardInterpState - save and restore an interpreter's state






SYNOPSIS


#include <tcl.h>

Tcl_InterpState
Tcl_SaveInterpState(interp, status)

int
Tcl_RestoreInterpState(interp, state)

Tcl_DiscardInterpState(state)






ARGUMENTS



  
Tcl_Interp *interp (in)

  
Interpreter for which state should be saved.

  
int status (in)

  
Return code value to save as part of interpreter state.

  
Tcl_InterpState state (in)

  
Saved state token to be restored or discarded.
    
    

    

  








DESCRIPTION


These routines allows a C procedure to take a snapshot of the
    current state of an interpreter so that it can be restored after a call to
    Tcl_Eval or some other routine that modifies the interpreter
  state.


Tcl_SaveInterpState stores a snapshot of the interpreter
    state in an opaque token returned by Tcl_SaveInterpState. That token
    value may then be passed back to one of Tcl_RestoreInterpState or
    Tcl_DiscardInterpState, depending on whether the interp state is to
    be restored. So long as one of the latter two routines is called, Tcl will
    take care of memory management.


Tcl_SaveInterpState takes a snapshot of those portions of
    interpreter state that make up the full result of script evaluation. This
    include the interpreter result, the return code (passed in as the
    status argument, and any return options, including -errorinfo
    and -errorcode when an error is in progress. This snapshot is
    returned as an opaque token of type Tcl_InterpState. The call to
    Tcl_SaveInterpState does not itself change the state of the
    interpreter.


Tcl_RestoreInterpState accepts a Tcl_InterpState
    token previously returned by Tcl_SaveInterpState and restores the
    state of the interp to the state held in that snapshot. The return value of
    Tcl_RestoreInterpState is the status value originally passed to
    Tcl_SaveInterpState when the snapshot token was created.


Tcl_DiscardInterpState is called to release a
    Tcl_InterpState token previously returned by
    Tcl_SaveInterpState when that snapshot is not to be restored to an
    interp.


The Tcl_InterpState token returned by
    Tcl_SaveInterpState must eventually be passed to either
    Tcl_RestoreInterpState or Tcl_DiscardInterpState to avoid a
    memory leak. Once the Tcl_InterpState token is passed to one of them,
    the token is no longer valid and should not be used anymore.






KEYWORDS


result, state, interp







  

    8.1
    Tcl