Why does re-opening a nested module give different results depending on the syntax used? For example, this works fine:
module A module E end end module A module E def E.e end end end
module A module E end end module A::E def E.e end end
gives the error:
reopen.rb:6:in `<module:E>': uninitialized constant A::E::E (NameError) from reopen.rb:5:in `<main>'
(Before someone points this out, a workaround is to use
self instead of the module name when defining Ee, but that's not really the point of this post.)
module keyword sets a namespace context that is checked for references to existing names of Modules. These namespaces are then searched inner-to-outer to resolve references to Module (and Class) names.
In your first example, it looks like you may need to define
module E block, but in fact you don't:
module A module E end end module A def E.e end end
What happens in both your examples is that Ruby looks at the current namespace, and tries
<namespace>::E as a module name. So in both examples, the first thing it checks is in fact
A::E::E which does not exist. Then it falls back to the next context. Which is where the examples differ: In the first example it is
A::E which is valid, in the second example, it is just
E which is not. The error that it then throws relates to the first name it checked.
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