Changes between Version 28 and Version 29 of WG1BallotGleckler


Ignore:
Timestamp:
06/29/11 02:11:18 (6 years ago)
Author:
aag
Comment:

Updated vote on #137 "Current-seconds semantics still open."

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  • WG1BallotGleckler

    v28 v29  
    354354 
    355355In issue #70, WG1 voted to make `current-seconds` an optional 
    356 procedure, but there is no guidance about what it returns.  The second 
    357 choice, TimeCowan, calls it `current-posix-second` and makes it return 
    358 the integral number of seconds since the Posix epoch, excluding all 
    359 leap seconds.  We need a final decision on name and semantics. 
    360  
    361 Need proposals. 
    362  
    363   * '''Options:''' 
    364   * '''Default:''' 
    365   * '''Preferences:''' 
     356procedure, but there is no guidance about what it returns. 
     357 
     358If we choose to specify this further, the big question is whether or 
     359not to include leap seconds - i.e. do we specify it as TAI or POSIX 
     360time (the choice of the epoch itself is less controversial and 
     361defaults to the POSIX epoch).  TAI time has the advantage that it 
     362measures real, unambiguous time, and two calls to current-seconds more 
     363than a second apart are guaranteed to actually differ.  POSIX time has 
     364the advantage of bug-for-bug compatibility with POSIX systems - the 
     365times are ambiguous, but they already have to deal with that. 
     366 
     367The other issue is whether to return an integral number of seconds and 
     368lose the ability to specify subsecond real times, or return an inexact 
     369real (flonum) number of seconds and have to deal with variable 
     370precision depending on the date. 
     371 
     372TimeCowan is equivalent to the `posix-integer` option, and in addition 
     373changes the name to `current-posix-second`. 
     374 
     375  * '''Proposals:''' 
     376    * '''cowan:''' TimeCowan 
     377    * '''posix-integer:''' POSIX time as an exact integer value 
     378    * '''posix-flonum:''' POSIX time as an inexact real value 
     379    * '''tai-integer:''' TAI time as an exact integer value 
     380    * '''tai-flonum:''' TAI time as an inexact real value 
     381  * '''Options:''' cowan, unspecified, undecided, none 
     382  * '''Default:''' unspecified 
     383  * '''Preferences:''' tai-integer, posix-integer, cowan, tai-flonum, posix-flonum 
     384 
     385Having a floating point representation seems even worse than using the POSIX representation.  I don't want floating point error in my time. 
    366386 
    367387=== #147 Allow literal file spec lists in include and include-ci ===