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
21 store the date and time informa‐
22 tion.
23 Tcl_GetTimeProc getProc (in) Pointer to handler function
25 replacing Tcl_GetTime's access
26 to the OS.
27 Tcl_ScaleTimeProc scaleProc (in) Pointer to handler function for
29 the conversion of time delays in
30 the virtual domain to real-time.
31 ClientData clientData (in) Value passed through to the two
33 handler functions.
34 Tcl_GetTimeProc *getProcPtr (out) Pointer to place the currently
36 registered get handler function
37 into.
38 Tcl_ScaleTimeProc *scaleProcPtr (out) Pointer to place the currently
40 registered scale handler func‐
41 tion into.
42 ClientData *clientDataPtr (out) Pointer to place the currently
44 registered pass-through value
45 into.
46______________________________________________________________________________
47
49 The Tcl_GetTime function retrieves the current time as a Tcl_Time
50 structure in memory the caller provides. This structure has the fol‐
51 lowing definition:
52 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 VIRTUALIZED TIME
74 The Tcl_SetTimeProc function registers two related handler functions
75 with the core. The first handler function is a replacement for Tcl_Get‐
76 Time, or rather the OS access made by Tcl_GetTime. The other handler
77 function is used by the Tcl notifier to convert wait/block times from
78 the virtual domain into real time.
79 The Tcl_QueryTimeProc function returns the currently registered handler
81 functions. If no external handlers were set then this will return the
82 standard handlers accessing and processing the native time of the OS.
83 The arguments to the function are allowed to be NULL; and any argument
84 which is NULL is ignored and not set.
85 The signatures of the handler functions are as follows:
87 typedef void Tcl_GetTimeProc(
89 Tcl_Time *timebuf,
90 ClientData clientData);
91 typedef void Tcl_ScaleTimeProc(
92 Tcl_Time *timebuf,
93 ClientData clientData);
94 The timebuf fields contain the time to manipulate, and the clientData
96 fields contain a pointer supplied at the time the handler functions
97 were registered.
98 Any handler pair specified has to return data which is consistent
100 between them. In other words, setting one handler of the pair to some‐
101 thing assuming a 10-times slowdown, and the other handler of the pair
102 to something assuming a two-times slowdown is wrong and not allowed.
103 The set handler functions are allowed to run the delivered time back‐
105 wards, however this should be avoided. We have to allow it as the
106 native time can run backwards as the user can fiddle with the system
107 time one way or other. Note that the insertion of the hooks will not
108 change the behavior of the Tcl core with regard to this situation, i.e.
109 the existing behavior is retained.
110
112 clock(n)
113
115 date, time
116Tcl 8.4 Tcl_GetTime(3)