API Reference for Enthought Tool Suite 3.2.0

Classes

• ContextFunctionError

Function summary

• args_to_locals(co)
• compile_bytecode(ops)
• context_function(f, context_factory)
• local_context(context_factory)
• parse_bytecode(bytes)
• patch_load_and_store(ops, argcount, nglobals, ncellandfreevars)

Functions

• args_to_locals(co)

  Turn arguments of a function into local variables in a code object

• compile_bytecode(ops)

  Take (operation, argument) tuples and return a bytecode string.

• context_function(f, context_factory)

  Allows a function to execute as if locals are a context

  This decorator modifies a function so that it uses contexts generated by a context_factory in place of the usual local dictionary. In most cases the context_factory function should return a fresh context on each call.

  Potential uses include:

  • over-riding internal globals by pre-inserting values into the local namespace (eg. replacing math with numpy in the function's namespace so that a function can be converted to use with arrays).
  • internal unit conversion
  • introspection of function operation

  This decorator works by re-writing the function's bytecode, so it will not work for functions coming from C extension modules. It also cannot currently work with functions that contain closures.

  Parameters

  f : function

  the function to be decorated

  context_factory : callable

  a callable that returns a context to be used as the function's local namespace

  Returns

  a function that can be used in place of f

  Examples

  Over-writing a global in a function using a pre-filled local context

  >>> import math
  >>> def f(x):
  ...     return 2*math.sin(x) + math.cos(x)
  >>> import numpy
  >>> def numpy_math_context():
  ...     return {'math': numpy}
  >>> f = context_function(f, numpy_math_context)
  >>> f(numpy.array([0, 0.5, 1])*numpy.pi)
  array([1.0, 2.1213203435596424, 2])
  

  Poor-man's closure:

  >>> def accumulator(value):
  ...     total += value
  >>> accumulation_dict = {'total': 0}
  >>> def accumulator_factory():
  ...     return accumulator_dict
  >>> accumulator = context_function(accumulator, accumulator_factory)
  >>> for i in range(10):
  ...     accumulator(i)
  >>> accumulation_dict['total']
  45
  

  Closure raises an exception:

  >>> def f(x):
  ...     a = 1
  ...     def g(y):
  ...         return y+a
  ...     return x+g(x)
  >>> context_function(f, dict)
  ContextFunctionError: can't create context_function for function containing closure
  

• local_context(context_factory)

  Decorator that specifies a context_factory to be used for this function

  This is a thin wrapper around a context_function call.

• parse_bytecode(bytes)

  Take a bytecode string and generate (operation, argument) tuples.

• patch_load_and_store(ops, argcount, nglobals, ncellandfreevars)

  Generator which replaces *_FAST and *_GLOBAL ops with *_NAME ops.

Imported Names

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