Agile Web Development with Rails 7: 'rails new demo' specifying the Rails version has no affect [solved]


Created the demo app with the following command from page 102:

work>​​ ​​rails​​ ​​new​​ ​​demo​

Examined the installation with the following command from page 104:

​demo>​​ ​​bin/rails​​ ​​about​

Output indicated Rails 7.0.5:

About your application's environment
Rails version             7.0.5

So I deleted the demo directory and ran the command, specifying the version:

rails _7.0.4_ new demo

Command bin/rails about still reports Rails 7.0.5. However, the Gemfile indicates 7.0.4:

gem "rails", "~> 7.0.4"

I presume 7.0.4 vs 7.0.5 is not going to make much of a difference. However, it would be nice to understand what’s going here.

FYI, gem list rails --local output:

*** LOCAL GEMS ***

importmap-rails (1.1.6)
rails (7.0.5, 7.0.4)
rails-dom-testing (2.0.3)
rails-html-sanitizer (1.6.0)
sprockets-rails (3.4.2)
stimulus-rails (1.2.1)
turbo-rails (1.4.0)

The page numbers in my original post seem wrong. Instead of pages 102 and 104, they should be 75 and 76, respectively. That said, I’m not sure I trust Apple Books. :laughing:

This is how RubyGems Semantic Versioning with Pessimistic version constraint works

gem "rails", "~> 7.0.4" # means >= 7.0.4 and < 7.1

Semantic versioning boils down to:

  • PATCH 0.0.x level changes for implementation level detail changes, such as small bug fixes
  • MINOR 0.x.0 level changes for any backwards compatible API changes, such as new functionality/features
  • MAJOR x.0.0 level changes for backwards incompatible API changes, such as changes that will break existing users code if they update

If you use a version specifier like "~> 7.0.4" bundler will always pick the latest patch of the given version 7.0 of the gem.

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 . ~> 0 is identical to >= 0.0 and < 1.0 .

1 Like

I’ve added an explanation and suggested replacing the twiddle-wakka with an equals sign.