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Diffstat (limited to 'guides/source/autoloading_and_reloading_constants.md')
-rw-r--r-- | guides/source/autoloading_and_reloading_constants.md | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/guides/source/autoloading_and_reloading_constants.md b/guides/source/autoloading_and_reloading_constants.md index c62194faf4..dea87a18f8 100644 --- a/guides/source/autoloading_and_reloading_constants.md +++ b/guides/source/autoloading_and_reloading_constants.md @@ -330,11 +330,17 @@ its resolution next. Let's define *parent* to be that qualifying class or module object, that is, `Billing` in the example above. The algorithm for qualified constants goes like this: -1. The constant is looked up in the parent and its ancestors. +1. The constant is looked up in the parent and its ancestors. In Ruby >= 2.5, +`Object` is skipped if present among the ancestors. `Kernel` and `BasicObject` +are still checked though. 2. If the lookup fails, `const_missing` is invoked in the parent. The default implementation of `const_missing` raises `NameError`, but it can be overridden. +INFO. In Ruby < 2.5 `String::Hash` evaluates to `Hash` and the interpreter +issues a warning: "toplevel constant Hash referenced by String::Hash". Starting +with 2.5, `String::Hash` raises `NameError` because `Object` is skipped. + As you see, this algorithm is simpler than the one for relative constants. In particular, the nesting plays no role here, and modules are not special-cased, if neither they nor their ancestors have the constants, `Object` is **not** @@ -954,7 +960,7 @@ to work on some subclass, things get interesting. While working with `Polygon` you do not need to be aware of all its descendants, because anything in the table is by definition a polygon, but when working with subclasses Active Record needs to be able to enumerate the types it is looking -for. Let’s see an example. +for. Let's see an example. `Rectangle.all` only loads rectangles by adding a type constraint to the query: @@ -963,7 +969,7 @@ SELECT "polygons".* FROM "polygons" WHERE "polygons"."type" IN ("Rectangle") ``` -Let’s introduce now a subclass of `Rectangle`: +Let's introduce now a subclass of `Rectangle`: ```ruby # app/models/square.rb @@ -978,7 +984,7 @@ SELECT "polygons".* FROM "polygons" WHERE "polygons"."type" IN ("Rectangle", "Square") ``` -But there’s a caveat here: How does Active Record know that the class `Square` +But there's a caveat here: How does Active Record know that the class `Square` exists at all? Even if the file `app/models/square.rb` exists and defines the `Square` class, @@ -1049,7 +1055,7 @@ end The purpose of this setup would be that the application uses the class that corresponds to the environment via `AUTH_SERVICE`. In development mode -`MockedAuthService` gets autoloaded when the initializer runs. Let’s suppose +`MockedAuthService` gets autoloaded when the initializer runs. Let's suppose we do some requests, change its implementation, and hit the application again. To our surprise the changes are not reflected. Why? @@ -1178,6 +1184,8 @@ end #### Qualified References +WARNING. This gotcha is only possible in Ruby < 2.5. + Given ```ruby |