Refer variables & closures defined in module from another file

Help & Support
1

Can someone please advise why I can refer to functions & macros from modules defined in another file but cannot refer to variables & closures from modules in another files. Though, I can include locally defined module from same file and can refer to variable & closure defined in it.

I am including inc.cr in main.cr and executing main.cr.

Crystal version 1.0.0 & LLVM 10.0.0

inc.cr

module Inc

  def incFunction : String
    "Include Function"
  end

  macro incMacro
    "Include Macro"
  end

  incClosure = ->{ "Include Closure" }

  incVar : String = "Include Var"

end

main.cr

require "./inc"

module MainModule
  mainClosure = -> { "Main Closure" }
  mainVar : String = "Main Var"
end

include Inc
include MainModule

puts mainClosure.call # => Main Closure
puts mainVar          # => Main Var

puts incFunction      # => Include Function
puts incMacro         # => Include Macro
puts incClosure.call  # => Error: undefined local variable or method 'incClosure' for top-level
puts incVar           # => Error: undefined local variable or method 'incVar' for top-level
2

Crystal has no global variables. Variables in the top-level scope are local variables scoped to the current file. Thus they’re inaccessible from other files.

Expressions directly inside a name space (i.e. not in a method or macro body) are part of the top-level scope of that file. The namespace does not create a nested scope. The variables defined in side MainModule are always accessible outside it, even without include MainModule.

3

In Ruby the variables are scoped (still inaccesible from outside). Ideally it should work like that in Crystal. Maybe for 2.0, but it’s a minor thing.

2 Likes
4

Thanks, I think this can be included in the documentation as it is mentioned here.

1 Like