“Boxed” version operator. Version must be greater than or equal to the specified version and less than the specified version after having its minor version number increased by 1. This is to avoid API incompatibilities between minor version releases.
http://gembundler.com/gemfile.html Most of the version specifiers, like >= 1.0, are self-explanatory. The specifier ~> has a special meaning, best shown by example. ~> 2.0.3 is identical to >= 2.0.3 and < 2.1. ~> 2.1 is identical to >= 2.1 and < 3.0. ~> 2.2.beta will match prerelease versions like 2.2.beta.12.
我之前问过，所以知道这个问题。
