In Ruby local variables only accessible in the scope that they are defined. Whenever you enter/leave a Class, a Module or a Method definiton your scope changes in Ruby. For instance : v1 = 1 class MyClass # SCOPE GATE: entering class v2 = 2 local_variables # => [“v2”] def my_method # SCOPE GATE: entering … Read more
As an additional information for future readers, starting from ruby 2.1.0 you can using binding.local_variable_get and binding.local_variable_set: def foo a = 1 b = binding b.local_variable_set(:a, 2) # set existing local variable `a’ b.local_variable_set(:c, 3) # create new local variable `c’ # `c’ exists only in binding. b.local_variable_get(:a) #=> 2 b.local_variable_get(:c) #=> 3 p a … Read more
Because in the first code, you have created a local variable var and used its value, whereas in the 2nd code, you are using the local variable var, without defining it. So, if you want to make your 2nd function work, you need to declare : – global var in the function before using var. … Read more
Python treats variables in functions differently depending on whether you assign values to them from inside or outside the function. If a variable is assigned within a function, it is treated by default as a local variable. Therefore, when you uncomment the line, you are trying to reference the local variable c before any value … Read more
Local variables always live on the stack, the moment method is over all local variables are gone. But your inner class objects might be on heap even after the method is over (Say an instance variable holds on to the reference), so in that case it cannot access your local variables since they are gone, … Read more
Within each category of storage classes (except dynamically allocated objects), objects are destructed in the reverse order of construction.
Yuval and David’s answers are basically correct; summing up: Use of an unassigned local variable is a likely bug, and this can be detected by the compiler at low cost. Use of an unassigned field or array element is less likely a bug, and it is harder to detect the condition in the compiler. Therefore … Read more
Ruby interpreter initializes a local variable with nil when it sees an assignment to it. It initializes the local variable before it executes the assignment expression or even when the assignment is not reachable (as in the example below). This means your code initializes a with nil and then the expression a = nil will … Read more
You have just stumbled on a js “feature” called hoisting var myname = “global”; // global variable function func() { alert(myname); // “undefined” var myname = “local”; alert(myname); // “local” } func(); In this code when you define func the compiler looks at the function body. It sees that you are declaring a variable called … Read more
This issue is somewhat discussed in the Python3 bug list. Ultimately, to get this behavior, you need to do: def foo(): ldict = {} exec(“a=3”,globals(),ldict) a = ldict[‘a’] print(a) And if you check the Python3 documentation on exec, you’ll see the following note: The default locals act as described for function locals() below: modifications to … Read more