Registry.py

## The one and only instance of `Registry`.
registry = None
 
class Registry:
    """
    Class that registers the various analysis tools for star polymers.
    """
 
    def __init__(self):
        """
        The constructor.
 
        This is called automatically by the encolsing file, and must not be
        called thereafter.
        """
        if registry is not None:
            raise Exception("Cannot create more than one instance")
 
        from collections import OrderedDict
        self._registry = OrderedDict()
 
 
    def register(self, cls):
        """
        Register the given class with the registry.
 
        @param[in] cls The class to register.
        """
 
        import inspect
 
        if not inspect.isclass(cls):
            raise ValueError()
 
        if cls.__name__ in self._registry:
            raise ValueError("Already in registry: " + cls.__name__)
 
        self._registry[cls.__name__] = cls
 
 
    def getRegisteredClasses(self):
        """
        Returns a dictionary of registered classes.
        """
 
        return self._registry
 
 
registry = Registry()