NAME

       Tcl_HandleAlloc,       Tcl_HandleFree,       Tcl_HandleTblInit,      Tcl_HandleTblRelease,
       Tcl_HandleTblUseCount,  Tcl_HandleWalk,  Tcl_HandleXlate  -  Dynamic,  handle  addressable
       tables.

SYNOPSIS

       #include <tclExtend.h>

       void_pt
       Tcl_HandleTblInit (const char *handleBase,
                          int         entrySize,
                          int         initEntries);

       int
       Tcl_HandleTblUseCount (void_pt  headerPtr,
                              int      amount);

       void
       Tcl_HandleTblRelease (void_pt headerPtr);

       void_pt
       Tcl_HandleAlloc (void_pt   headerPtr,
                        char     *handlePtr);

       void_pt
       Tcl_HandleXlate (Tcl_Interp *interp,
                        void_pt     headerPtr,
                        const char *handle);

       void_pt
       Tcl_HandleWalk (void_pt   headerPtr,
                       int      *walkKeyPtr);

       void
       Tcl_WalkKeyToHandle (void_pt   headerPtr,
                            int       walkKey,
                            char     *handlePtr);

       void
       Tcl_HandleFree (void_pt headerPtr,
                       void_pt entryPtr);

DESCRIPTION

       The Tcl handle facility provides a way to manage table entries that may be referenced by a
       textual handle from Tcl code.  This is provided for applications that need to create  data
       structures  in  one  command,  return  a  reference (i.e. pointer) to that particular data
       structure and then access that data structure in other commands. An example application is
       file handles.

       A  handle  consists  of a base name, which is some unique, meaningful name, such as `file'
       and a numeric value appended to the base name (e.g.  `file3').   The  handle  facility  is
       designed  to  provide  a  standard  mechanism  for building Tcl commands that allocate and
       access table entries based on an entry  index.   The  tables  are  expanded  when  needed,
       consequently  pointers to entries should not be kept, as they will become invalid when the
       table is expanded.  If the table entries are  large  or  pointers  must  be  kept  to  the
       entries,  then  the  the  entries  should be allocated separately and pointers kept in the
       handle table.  A use count is kept on the table.  This use count is intended to  determine
       when a table shared by multiple commands is to be release.

   Tcl_HandleTblInit
       Create  and  initialize  a Tcl dynamic handle table.  The use count on the table is set to
       one.

       Parameters:
         o handleBase - The base name of the handle, the handle will  be  returned  in  the  form
         "baseNN", where NN is the table entry number.
         o entrySize - The size of an entry, in bytes.
         o initEntries - Initial size of the table, in entries.

       Returns:
         A pointer to the table header.

   Tcl_HandleTblUseCount
       Alter  the  handle  table  use  count  by  the  specified amount, which can be positive or
       negative.  Amount may be zero to retrieve the use count.

       Parameters:
         o headerPtr - Pointer to the table header.
         o amount - The amount to alter the use count by.

       Returns:
         The resulting use count.

   Tcl_HandleTblRelease
       Decrement the use count on a Tcl dynamic handle table.  If  the  count  goes  to  zero  or
       negative, then release the table.

       Parameters:
         o headerPtr - Pointer to the table header.

   Tcl_HandleAlloc
       Allocate an entry and associate a handle with it.

       Parameters:
         o headerPtr - A pointer to the table header.
         o handlePtr - Buffer to return handle in. It must be big enough to hold the name.

       Returns:
         A pointer to the allocated entry (user part).

   Tcl_HandleXlate
       Translate a handle to a entry pointer.

       Parameters:
         o interp - A error message may be returned in result.
         o headerPtr - A pointer to the table header.

         o handle - The handle assigned to the entry.

       Returns:
         A pointer to the entry, or NULL if an error occurred.

   Tcl_HandleWalk
       Walk through and find every allocated entry in a table.  Entries may be deallocated during
       a walk, but should not be allocated.

       Parameters:
         o headerPtr - A pointer to the table header.
         o walkKeyPtr - Pointer to a variable to use to keep track of the  place  in  the  table.
         The variable should be initialized to -1 before the first call.
       Returns:
         A pointer to the next allocated entry, or NULL if there are not more.

   Tcl_WalkKeyToHandle
       Convert  a  walk  key,  as  returned  from  a  call  to Tcl_HandleWalk into a handle.  The
       Tcl_HandleWalk must have succeeded.

       Parameters:
         o headerPtr - A pointer to the table header.
         o walkKey - The walk key.
         o handlePtr - Buffer to return handle in. It must be big enough to hold the name.

   Tcl_HandleFree
       Frees a handle table entry.

       Parameters:
         o headerPtr - A pointer to the table header.
         o entryPtr - Entry to free.