From CVS to Git

There has been an exodus of Ruby developers recently, moving from Subversion to Git for SCM. Being a happy CVS user, I was curious about what Git could offer for a team of one developer.

After understanding the workflow used by experienced Git users and its benefits, I started to think the other way around: why use CVS when I can use Git.

Then I decided to move binpatch and Ruby/Informix repositories to github.com. Forking, contributing or just tracking the changes is now easier, through an easy to use interface, source code browser with history and RSS feeds.

The following links were especially useful to make the switch:

• Git User's Manual
  
• Git for CVS users
• Git - SVN Crash Course

Binpatch and Ruby/Informix repositories can be found here.

Ruby/Informix 0.7.0 released

Yesterday night Ruby/Informix 0.7.0 escaped from my hands, after a vacational sprint that allowed Ruby/Informix to get new and important capabilities. The most obvious one is the support for the INTERVAL data type.

Actually, Ruby/Informix was able to handle insertion of INTERVAL data types already, because Informix accepts an ANSI SQL standard formatted string as an INTERVAL. Today, we can still use a String or use an Interval object for storing and also for retrieving INTERVAL data.

To create an Interval object you can write the following:

Interval = Informix::Interval # for short

ym = Interval.year_to_month(2, 5) #=> "2-05"
ds = Interval.day_to_second(1, 2,
3, 4) #=> "1 02:03:04.00000"

ym is an INTERVAL YEAR TO MONTH, while ds is an INTERVAL DAY TO FRACTION.

You don't need to specify all the fields of an INTERVAL.

# the rest of the fields are zero
Interval.year_to_month(2) #=> "2-00"
Interval.day_to_second(5) #=> "5 00:00:00.00000"

# using a hash
Interval.year_to_month(:months => 3) #=> "0-03"
Interval.day_to_second(:hours => 2,
:minutes => 5) #=> "0 02:05:00.00000"

You can even use fractions of years, days, hours, minutes or seconds:

Interval.year_to_month(1.5) #=> "1-06"
Interval.day_to_second(:hours => 1.5,
:minutes => 5) #=> "0 01:35:00.00000"

You can use Rationals instead of Floats for exactitud:

# a third of an hour?, not quite
Interval.year_to_month(0.3) #=> "0 00:18:00.00000"

# this is exact
Interval.year_to_month(Rational(1,3)) #=> "0 00:20:00.00000"

This is specially important when working with small fractions of seconds:

Interval.day_to_second(:days=>123456789,
:seconds=>1.2) #=> "123456789 00:00:01.19922"
Interval.day_to_second(:days=>123456789,
:seconds=>Rational(12,10)) #=> "123456789 00:00:01.20000"

Because when using Floats, there's a limit in the significant digits that can be stored that doesn't exist when using a Rational.

Interval objects have the ability to work with Date, DateTime and Time Ruby objects:

# YEAR TO MONTH an Date
ym = Interval.year_to_month(1, 5) #=> "1-05"
today = Date.today #=> "2008-04-01"
ym + today #=> "2009-09-01"


# DAY TO SECOND and Time
ds = Interval.day_to_second(:hours=>3,
:minutes=> 10) #=> "0 03:10:00.00000"
now = Time.now #=> "2008-04-01 19:58:04.856533"
ds + now #=> "2008-04-01 23:08:04.856533"

You can't mix INTERVAL YEAR TO MONTH with Time, or INTERVAL DAY TO FRACTION with Date, because are incompatible. If you still want to do something like that, you can use DateTime:

now = DateTime.now #=> "2008-04-01 20:21:42"
ym = Interval.year_to_month(1, 5) #=> "1-05"
ds = Interval.day_to_second(:hours=>3,
:minutes=> 10) #=> "0 03:10:00.00000"

ym + now #=> "2009-09-01 20:21:42"
ds + now #=> "2008-04-01 23:31:42"

But there's still more. What about if I want to know how many minutes are in 3 days and 4 hours?

ds = Interval.day_to_second(:days=> 3,
:hours=> 4) #=> "3 04:00:00.00000"
ds.to_minutes #=> 4560.0

What about seconds

ds.to_seconds #=> 273600

There are some things left to learn about Intervals, but this post has become too long. Don't forget to check the documentation, which has been enriched with more examples.