Any gem inclusion without a version number indicates 'latest' version of gem should be used.
Specifying a gem as such:
gen 'foo', '=3.0'
indicates a specific version must be used.
Specifying a gem as such
gem 'foo', '>= 3.0'
indicates a version >= 3.0 is suitable. In general, you get what you expect from
= Equals version
!= Not equal to version
> Greater than version
< Less than version
>= Greater than or equal to
<= Less than or equal to
Gem versions can also be specified with the 'approximately greater than' operator. This operator increment final digit of a version up until next significant digit would turn over. So, a gem specification of
gem 'foo', '~> 3.1'
is satisfied with any version from 3.1 up to 3.9. inclusive. If three digits are specified in a version number used with ~> operator, as below
gem 'foo', '~> 3.1.1'
then the gem versions compatible with the application are 3.1.1 through 3.1.9, inclusive.
