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Source code for galaxy.util.none_like

"""
Objects with No values
"""

from galaxy.datatypes.registry import Registry
from galaxy.model.metadata import MetadataCollection


class RecursiveNone(object):
    def __str__(self):
        return "None"

    def __repr__(self):
        return str(self)

    def __getattr__(self, name):
        value = RecursiveNone()
        setattr(self, name, value)
        return value

    def __nonzero__(self):
        return False


class NoneDataset(RecursiveNone):
    def __init__(self, datatypes_registry=None, ext='data', dbkey='?'):
        self.ext = self.extension = ext
        self.dbkey = dbkey
        if datatypes_registry is None:
            # Default Value Required for unit tests
            datatypes_registry = Registry()
            datatypes_registry.load_datatypes()
        self.datatype = datatypes_registry.get_datatype_by_extension(ext)
        self._metadata = None
        self.metadata = MetadataCollection(self)

    def __getattr__(self, name):
        return "None"

    def missing_meta(self):
        return False