Ruby Language Dynamic Evaluation Evaluating Inside a Binding
Example
Ruby keeps track of local variables and self variable via an object called binding. We can get binding of a scope with calling Kernel#binding and evaluate string inside a binding via Binding#eval.
b = proc do
local_variable = :local
binding
end.call
b.eval "local_variable" #=> :local
def fake_class_eval klass, source = nil, &block
class_binding = klass.send :eval, "binding"
if block
class_binding.local_variable_set :_fake_class_eval_block, block
class_binding.eval "_fake_class_eval_block.call"
else
class_binding.eval source
end
end
class Example
end
fake_class_eval Example, <<-BLOCK
def self.foo
:foo
end
BLOCK
fake_class_eval Example do
def bar
:bar
end
end
Example.foo #=> :foo
Example.new.bar #=> :bar
