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Tcl_GetTime(3)                             Tcl Library Procedures                             Tcl_GetTime(3)



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NAME
       Tcl_GetTime, Tcl_SetTimeProc, Tcl_QueryTimeProc - get date and time

SYNOPSIS
       #include <tcl.h>

       Tcl_GetTime(timePtr)

       Tcl_SetTimeProc(getProc, scaleProc, clientData)

       Tcl_QueryTimeProc(getProcPtr, scaleProcPtr, clientDataPtr)

ARGUMENTS
       Tcl_Time * timePtr (out)         Points to memory in which to store the date and time information.

       Tcl_GetTimeProc * getProc (in)          Pointer to handler function replacing Tcl_GetTime's access to
                                               the OS.

       Tcl_ScaleTimeProc * scaleProc (in)          Pointer to handler function for the  conversion  of  time
                                                   delays in the virtual domain to real-time.

       ClientData * clientData (in)          Value passed through to the two handler functions.

       Tcl_GetTimeProc ** getProcPtr (inout)       Pointer  to  place  the  currently registered get handler
                                                   function into.

       Tcl_ScaleTimeProc ** scaleProcPtr (inout)       Pointer to place the currently registered scale  han-dler handler
                                                       dler function into.

       ClientData ** clientDataPtr (inout)       Pointer  to  place  the  currently  registered pass-through
                                                 value into.
____________________________________________________________________________________________________________

DESCRIPTION
       The Tcl_GetTime function retrieves the current time as a Tcl_Time structure in memory the caller pro-vides. provides.
       vides.  This structure has the following definition:
              typedef struct Tcl_Time {
                  long sec;
                  long usec;
              } Tcl_Time;

       On  return, the sec member of the structure is filled in with the number of seconds that have elapsed
       since the epoch: the epoch is the point in time of 00:00 UTC, 1 January 1970.  This number  does  not
       count leap seconds - an interval of one day advances it by 86400 seconds regardless of whether a leap
       second has been inserted.

       The usec member of the structure is filled in with the number of microseconds that have elapsed since
       the start of the second designated by sec.  The Tcl library makes every effort to keep this number as
       precise as possible, subject to the limitations of the computer system.  On  multiprocessor  variants
       of Windows, this number may be limited to the 10- or 20-ms granularity of the system clock.  (On sin-gle-processor single-processor
       gle-processor Windows systems, the usec field is derived from a performance  counter  and  is  highly
       precise.)

       The  Tcl_SetTime  function  registers  two related handler functions with the core. The first handler
       function is a replacement for Tcl_GetTime, or rather the OS access made  by  Tcl_GetTime.  The  other
       handler function is used by the Tcl notifier to convert wait/block times from the virtual domain into
       real time.

       The Tcl_QueryTime function returns the currently registered handler functions. If  no  external  han-dlers handlers
       dlers  were  set then this will return the standard handlers accessing and processing the native time
       of the OS. The arguments to the function are allowed to be NULL; and any argument which  is  NULL  is
       ignored and not set.

       Any  handler pair specified has to return data which is consistent between them. In other words, set-ting setting
       ting one handler of the pair to something assuming a 10-times slowdown, and the other handler of  the
       pair to something assuming a two-times slowdown is wrong and not allowed.

       The  set  handler  functions  are allowed to run the delivered time backwards, however this should be
       avoided. We have to allow it as the native time can run backwards as the user  can  fiddle  with  the
       system  time  one way or other. Note that the insertion of the hooks will not change the behaviour of
       the Tcl core with regard to this situation, i.e. the existing behaviour is retained.

SEE ALSO
       clock

KEYWORDS
       date, time



Tcl                                                  8.4                                      Tcl_GetTime(3)