1Tcl_GetTime(3) Tcl Library Procedures Tcl_GetTime(3)
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8 Tcl_GetTime, Tcl_SetTimeProc, Tcl_QueryTimeProc - get date and time
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11 #include <tcl.h>
12 Tcl_GetTime(timePtr)
14 Tcl_SetTimeProc(getProc, scaleProc, clientData)
16 Tcl_QueryTimeProc(getProcPtr, scaleProcPtr, clientDataPtr)
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20 Tcl_Time * timePtr (out) Points to memory in which to store the
21 date and time information.
22 Tcl_GetTimeProc * getProc (in) Pointer to handler function
24 replacing Tcl_GetTime's access
25 to the OS.
26 Tcl_ScaleTimeProc * scaleProc (in) Pointer to handler function
28 for the conversion of time
29 delays in the virtual
30 domain to real-time.
31 ClientData * clientData (in) Value passed through to the two
33 handler functions.
34 Tcl_GetTimeProc ** getProcPtr (inout) Pointer to place the cur‐
36 rently registered get han‐
37 dler function into.
38 Tcl_ScaleTimeProc ** scaleProcPtr (inout) Pointer to place the
40 currently registered
41 scale handler function
42 into.
43 ClientData ** clientDataPtr (inout) Pointer to place the cur‐
45 rently registered pass-
46 through value into.
47_________________________________________________________________
48
50 The Tcl_GetTime function retrieves the current time as a Tcl_Time
51 structure in memory the caller provides. This structure has the fol‐
52 lowing definition:
53 typedef struct Tcl_Time {
54 long sec;
55 long usec;
56 } Tcl_Time;
57 On return, the sec member of the structure is filled in with the number
59 of seconds that have elapsed since the epoch: the epoch is the point in
60 time of 00:00 UTC, 1 January 1970. This number does not count leap
61 seconds - an interval of one day advances it by 86400 seconds regard‐
62 less of whether a leap second has been inserted.
63 The usec member of the structure is filled in with the number of
65 microseconds that have elapsed since the start of the second designated
66 by sec. The Tcl library makes every effort to keep this number as pre‐
67 cise as possible, subject to the limitations of the computer system.
68 On multiprocessor variants of Windows, this number may be limited to
69 the 10- or 20-ms granularity of the system clock. (On single-processor
70 Windows systems, the usec field is derived from a performance counter
71 and is highly precise.)
72 The Tcl_SetTime function registers two related handler functions with
74 the core. The first handler function is a replacement for Tcl_GetTime,
75 or rather the OS access made by Tcl_GetTime. The other handler function
76 is used by the Tcl notifier to convert wait/block times from the vir‐
77 tual domain into real time.
78 The Tcl_QueryTime function returns the currently registered handler
80 functions. If no external handlers were set then this will return the
81 standard handlers accessing and processing the native time of the OS.
82 The arguments to the function are allowed to be NULL; and any argument
83 which is NULL is ignored and not set.
84 Any handler pair specified has to return data which is consistent
86 between them. In other words, setting one handler of the pair to some‐
87 thing assuming a 10-times slowdown, and the other handler of the pair
88 to something assuming a two-times slowdown is wrong and not allowed.
89 The set handler functions are allowed to run the delivered time back‐
91 wards, however this should be avoided. We have to allow it as the
92 native time can run backwards as the user can fiddle with the system
93 time one way or other. Note that the insertion of the hooks will not
94 change the behaviour of the Tcl core with regard to this situation,
95 i.e. the existing behaviour is retained.
96
98 clock
99
101 date, time
102Tcl 8.4 Tcl_GetTime(3)