Is there anyway to access foo from GetVar.print_foo?
foo = "test"
module GetVar
def self.print_foo
puts foo
end
end
GetVar.print_foo
I was able to get it to work by changing foo to a constant FOO, but this is more of a hack and I am looking for a better solution. I also can't, or rather prefer not, to make foo an instance variable @foo.
The simple answer is: no, there is no way to access the local variable foo in the script scope from the method scope of the print_foo method. foo is a local variable, local variables are local to the scope they are defined in, that's why they are called "local" variables, after all.
foo is defined in the script scope. It is not defined in the method scope of print_foo, ergo, it cannot be accessed from print_foo.
There are four local variable scopes in Ruby: script, module / class definition, method definition, and lambda literal / block body. Of these four, script scope, module / class scope, and method scope create new scopes. Lambda literals and blocks, and only those two create nested scopes that can access local variables from their surrounding lexical scopes.
So, the only way to get access to foo in print_foo is to make sure that print_foo is defined in a nested scope, i.e. in a block, and that all the surrounding scopes are also blocks. Thankfully, there is a method for defining methods called Module#define_method (or in this case actually Object#define_singleton_method) that takes a block, and there is a method for defining a module called Module::new that also takes a block:
Is there anyway to access foo from GetVar.print_foo?
foo = "test"
GetVar = Module.new do
define_singleton_method(:print_foo) do puts foo end
end
GetVar.print_foo
# test
Actually, we don't even need the block form of Module::new:
foo = "test"
GetVar = Module.new.tap do |m| m.define_singleton_method(:print_foo) do puts foo end end
GetVar.print_foo
# test
Use class_eval
class A
@foo = "test"
end
module GetVar
def self.print_foo
A.class_eval do
puts @foo
end
end
end
GetVar.print_foo
#=> "test"
or flattening the scope
foo = "test"
GetVar = Module.new do
# define a class method
define_singleton_method :print_foo do
puts foo
end
end
GetVar.print_foo
#=> "test"
See this question: How to understand the difference between class_eval() and instance_eval()?
def self.foo; "test"; endinside the module.verify_recaptcha, but the helper function creates a new scope that does not have the function I need from the recaptcha gem.$foo), but don't do that unless you have very good reason to do so. As Aetherus said, this looks more like a design problem to me.