What is a Scope?

A scope is the most basic interpretation class. You can think of it as a glorified hashmap which can inherit. It's structure is:

             Scope
               |
  +------------+------------+
  |            |            |
scope     inheritance   interface
             chain          |
                        +---+---+
                        |   |   |
                       get set has

What is each part?:

  • scope: a hashmap. The key is the variable name, the value is the value of the variable (this is usually a CheddarVariable, described later).
  • inheritance chain: this is either another Scope class, or null. If this exists, its scope will also be navigated, acting as inheritance. This is so the class being inherited from is modified itself, rather than a copy of it.
  • interface: this provides a very raw interface for getting a variable, setting a variable, or checking if it has a variable. These can be overwritten, but these methods are not to be confused with getters and setters.

All together this class can implement scopes. Here's an (psuedo-code) example of what is called when (the path the program takes is highlighted with +):

a = 1;     + interface/set(a, 1)
           - if inheritance chain/has(a)
           -    inheritance chain/set(a, 1)
           + else
           +    scope/set(a, 1)

{
    a = 1  + interface/set(a, 1)
           + if inheritance chain/has(a)
           +    inheritance chain/set(a, 1)
           - else
           -    scope/set(a, 1)
}

print a;   + interface/get(a)
           - if inheritance chain/has(a)
           -    inheritance chain/get(a)
           + else
           +    scope/get(a, 1)

results matching ""

    No results matching ""