我想让PyYAML的加载程序将映射(和有序映射)加载到Python 2.7+ OrderedDict类型中,而不是dict它当前使用的普通和对列表。
dict
最好的方法是什么?
注意 :有一个基于以下答案的库,该库还实现了CLoader和CDumpers:Phynix / yamlloader
我非常怀疑这是最好的方法,但这是我想出的方法,并且确实有效。也可作为要点。
import yaml import yaml.constructor try: # included in standard lib from Python 2.7 from collections import OrderedDict except ImportError: # try importing the backported drop-in replacement # it's available on PyPI from ordereddict import OrderedDict class OrderedDictYAMLLoader(yaml.Loader): """ A YAML loader that loads mappings into ordered dictionaries. """ def __init__(self, *args, **kwargs): yaml.Loader.__init__(self, *args, **kwargs) self.add_constructor(u'tag:yaml.org,2002:map', type(self).construct_yaml_map) self.add_constructor(u'tag:yaml.org,2002:omap', type(self).construct_yaml_map) def construct_yaml_map(self, node): data = OrderedDict() yield data value = self.construct_mapping(node) data.update(value) def construct_mapping(self, node, deep=False): if isinstance(node, yaml.MappingNode): self.flatten_mapping(node) else: raise yaml.constructor.ConstructorError(None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark) mapping = OrderedDict() for key_node, value_node in node.value: key = self.construct_object(key_node, deep=deep) try: hash(key) except TypeError, exc: raise yaml.constructor.ConstructorError('while constructing a mapping', node.start_mark, 'found unacceptable key (%s)' % exc, key_node.start_mark) value = self.construct_object(value_node, deep=deep) mapping[key] = value return mapping