Effect of leaving space after '-' in Ruby expression
date, math, ruby, ruby-on-rails
Solution
What actually happens is this:
Date.today(-29.days) # => Fri, 07 Feb 2014
`today` has an optional parameter called `start`, which defaults to `Date::ITALY`.
An optional argument the day of calendar reform (start) as a Julian day number, which should be 2298874 to 2426355 or -/+oo. The default value is Date::ITALY (2299161=1582-10-15).
Passing `-29.days` to `today` apparently has no effect.
Whereas:
Date.today + -29.days # => Thu, 09 Jan 2014
Which is the same as:
Date.today - 29.days # => Thu, 09 Jan 2014
Problem
Today I was trying something out in my Rails console and this happened, ``` 2.0.0p247 :009 > Date.today -29.days => Fri, 07 Feb 2014 2.0.0p247 :010 > Date.today - 29.days => Thu, 09 Jan 2014 ``` I am pretty baffled. I can see that I am missing something basic. But it just inst striking my mind! Could anyone explain why this is happening?