How NOT to market your favorite programming language

My dislike of Java is probably at least as strong as that of Obie Fernandez, but his blog post attacking Java is simply not an acceptable way to debate the matter. [I was alerted to this post by Blaine Buxton].

The author is also flat out wrong on a few major points, most notably the importance of good dev tools. I've found that the better the programmer, the more good tools help: They amplify whatever you've got to give. And I'd take a great programmer using Java over a poor one using any other language. The "dirty little secret" of IT is that quality of personnel matters far more than tools.

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• Chronos blog home page
• Chronos Date/Time Library web site

Comparative Examples: Chronos (and Smalltalk) vs. Java's Calendar Class

David Herron blogs about his attempt to use Java to show the local date and time of a widespread set of team members in Santa Clara CA, Beijing China, Bangalore India, Hyderabad India, St. Petersburg Russia and Dublin Ireland. His situation is becoming much more common, especially among IT professionals.

To see his Java code, and the resulting output, click here.

Here's the equivalent code using Chronos (and Smalltalk):

| universalNow printPolicy |
printPolicy := ConfigurableChronosPrintPolicy applying: #(showTimeZoneVerbosely).
universalNow := Timepoint utNow.
#('America/Los_Angeles' 'Asia/Calcutta' 'Europe/Moscow' 'Europe/Prague' 'Europe/Dublin' 
'Europe/London' 'Asia/Tokyo' 'Asia/Novosibirsk' 'Asia/Hong_Kong' 'Asia/Shanghai' 
'Asia/Seoul' 'America/Denver' 'America/New_York')
    do: [:tzKey | 
        | localTimeNow |
        localTimeNow := universalNow >> tzKey.
        Transcript 
            cr; 
            show: (localTimeNow % printPolicy)]

The code above produces the following output:

2006-01-26T19:51:43.248535-08:00 (PST:America/Los_Angeles)
2006-01-27T09:21:43.248535+05:30 (IST:Asia/Calcutta)
2006-01-27T06:51:43.248535+03:00 (MSK:Europe/Moscow)
2006-01-27T04:51:43.248535+01:00 (CET:Europe/Prague)
2006-01-27T03:51:43.248535+00:00 (GMT:Europe/Dublin)
2006-01-27T03:51:43.248535+00:00 (GMT:Europe/London)
2006-01-27T12:51:43.248535+09:00 (JST:Asia/Tokyo)
2006-01-27T09:51:43.248535+06:00 (NOVT:Asia/Novosibirsk)
2006-01-27T11:51:43.248535+08:00 (HKT:Asia/Hong_Kong)
2006-01-27T11:51:43.248535+08:00 (CST:Asia/Shanghai)
2006-01-27T12:51:43.248535+09:00 (KST:Asia/Seoul)
2006-01-26T20:51:43.248535-07:00 (MST:America/Denver)
2006-01-26T22:51:43.248535-05:00 (EST:America/New_York)

To get output formatted as RFC 2822, just replace "% printPolicy" with "% #rfc2822". To get output formatted according to the user's default preferences, replace "% printPolicy" with "localePrintString".

With the following improvements, we can sort the output by time zone offset, and get much more readable output:

| universalNow printPolicy |
printPolicy := ConfigurableChronosPrintPolicy applying:
                  #(showDayOfWeekAbbreviation 
                  useDayMonthYearOrder 
                  useMonthAbbreviation 
                  dateSeparator: $ 
                  dateAndTimeSeparator: $ 
                  hideSubsecondFraction
                  timeZoneSeparator: $ 
                  timeZoneElementSeparator: nil
                  showTimeZoneVerbosely).
universalNow := Timepoint utNow.
#('America/Los_Angeles' 'Asia/Calcutta' 'Europe/Moscow' 'Europe/Prague' 'Europe/Dublin' 
'Europe/London' 'Asia/Tokyo' 'Asia/Novosibirsk' 'Asia/Hong_Kong' 'Asia/Shanghai' 
'Asia/Seoul' 'America/Denver' 'America/New_York')
    collect: [:tzKey | universalNow >> tzKey]) 
      asSortedCollection: 
          [:localTimeA :localTimeB | localTimeA offset > localTimeB offset]) 
              do: [:localTime | Transcript cr; show: localTime % printPolicy]

The improved code produces the following output:

Fri, 27 Jan 2006 14:29:43 +0900 (KST: Asia/Seoul)
Fri, 27 Jan 2006 14:29:43 +0900 (JST: Asia/Tokyo)
Fri, 27 Jan 2006 13:29:43 +0800 (CST: Asia/Shanghai)
Fri, 27 Jan 2006 13:29:43 +0800 (HKT: Asia/Hong_Kong)
Fri, 27 Jan 2006 11:29:43 +0600 (NOVT: Asia/Novosibirsk)
Fri, 27 Jan 2006 10:59:43 +0530 (IST: Asia/Calcutta)
Fri, 27 Jan 2006 08:29:43 +0300 (MSK: Europe/Moscow)
Fri, 27 Jan 2006 06:29:43 +0100 (CET: Europe/Prague)
Fri, 27 Jan 2006 05:29:43 +0000 (GMT: Europe/London)
Fri, 27 Jan 2006 05:29:43 +0000 (GMT: Europe/Dublin)
Fri, 27 Jan 2006 00:29:43 -0500 (EST: America/New_York)
Thu, 26 Jan 2006 22:29:43 -0700 (MST: America/Denver)
Thu, 26 Jan 2006 21:29:43 -0800 (PST: America/Los_Angeles)

Perhaps David should have considered using Joda Time, if he's determined to use Java.

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• Chronos blog home page
• Chronos Date/Time Library web site

Chronos: A Few Comparative Examples

The home page for the Joda Date/Time Library presents some examples intended to demonstrate the "look and feel" of using Joda-Time. To see the Joda examples, click the link in the previous sentence.

Here are the equivalent examples using Chronos:

daysToNewYear: fromDate [Alternative 1]
    ^CalendarDuration days: (fromDate daysInYear - fromDate dayOfYear + 1)

daysToNewYear: fromDate [Alternative 2]
    ^CalendarDuration days: (fromDate daysUntil: (fromDate nextYear withDayOfYear: 1))

isRentalOverdue: datetimeRented [Alternative 1]
    "Answer whether a rental made on <datetimeRented> is now overdue."
    ^datetimeRented + 2.5 days < DateAndTime now

isRentalOverdue: datetimeRented [Alternative 2]
    "Answer whether a rental made on <datetimeRented> is now overdue."
    ^datetimeRented + (CivilDuration days: 2 hours: 12) < DateAndTime now

joinedInLastThreeMonths: datetimeJoined
    "Answer whether the <datetimeJoined> is within the past three months."
    ^(DateAndTime now withDuration: -3 months) includes: datetimeJoined

getBirthMonthText: dateOfBirth forLocale: localeKey
    "Answer the name of the month of <dateOfBirth> according to the locale identified by the <localeKey>."
    ^dateOfBirth
            forLocale: localeKey
            monthNameIfResolvable:
                [:monthName | monthName]
            ifNot:
                [dateOfBirth monthName]

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• Chronos blog home page
• Chronos Date/Time Library web site