4. A Plain Java Object Interpreter

In this chapter we start afresh on a third model run-time system in sub-project rt3.

We will test a series of ideas that may make it possible to treat any Java object as a Python object. Jython 2 achieves this by wrapping objects that are not instances of some sub-class of PyObject in a proxy. We will attempt to do this so that the interpreter (or compiled code) handles the object directly.

Concepts developed in sub-project rt2 will be heavily re-used.

• 4.1. Introduction
  • 4.1.1. Motivations
  • 4.1.2. Design Concept
  • 4.1.3. Feasibility
• 4.2. Operations on Built-in Types
  • 4.2.1. Direction of Travel
  • 4.2.2. PyType and Operations for float
    • A Unary Operation float.__neg__
      • Descriptive Structures
      • Method Implementations
      • Forming a PyWrapperDescr for __neg__
      • Slots in the Operations object
      • An Implication for Bootstrapping
      • Abstract API negative()
      • Constructing a Unary CallSite
    • A Binary Operation float.__sub__
      • Implementing __sub__ and __rsub__
      • Abstract API subtract()
      • Binary Class-Specific Methods
      • Constructing a Binary CallSite
  • 4.2.3. PyType and Operations for int and bool
    • The Unary Operation int.__neg__
    • Accepting and Adopting Boolean
  • 4.2.4. Continuing on Course
  • 4.2.5. Some Dots on the RADAR
• 4.3. Hash, Lookup and Dictionary
  • 4.3.1. The Type str
  • 4.3.2. Plain Object Keys and dict
    • Problems Posed by Object.hashCode()
    • Problems Posed by Object.equals()
    • Changes to dict
  • 4.3.3. Attribute Names
  • 4.3.4. The Dictionary of a PyType
• 4.4. Methods on Built-in Types
  • 4.4.1. The Visible Classes
    • Instance Methods
    • Static Methods
      • Comparison with static methods in Python
      • Posing an unwrapped builtin_function_or_method
      • Summary
    • Class Methods
  • 4.4.2. Relationships amongst the Classes
    • Instance Methods
    • Static Methods
    • Class Methods
  • 4.4.3. Design Features
    • Natural Parameter Types
    • Callable PyJavaFunction
    • Callable PyMethodDescr
    • Variants for Static and Class Methods
    • Using PythonStaticMethod
    • Efficient calls from CPython byte code
      • Calling a PyJavaFunction as a function
      • Calling a PyMethodDescr as a method
    • Prospect of efficient invokedynamic call sites
    • Common Code with Python Methods
  • 4.4.4. Annotations identifying Python Methods
    • Using PythonStaticMethod
• 4.5. Python Modules in Java
  • 4.5.1. Objectives
  • 4.5.2. Module Data Structures
    • Definition and Instance Structures
      • CPython’s approach
      • A Java approach
  • 4.5.3. An Attempt at builtins
    • Using PythonStaticMethod
    • Using PythonMethod
• 4.6. Creation and Initialisation
  • 4.6.1. type.__call__
  • 4.6.2. __new__
    • Comparison with other static methods
    • A Java implementation of __new__
    • A MethodHandle for __new__