在pyyaml中，SafeLoader不包含python本机类??型的加载程序，仅包含yaml规范中定义的类型。你可以看到类型的SafeLoader和Loader这里下面的互动样本。
您可以定义一个新的Loader类，该类添加了python元组，但未添加其他类型，因此它仍然非常安全：
import yaml
class PrettySafeLoader(yaml.SafeLoader):
def construct_python_tuple(self, node):
return tuple(self.construct_sequence(node))
PrettySafeLoader.add_constructor(
u'tag:yaml.org,2002:python/tuple',
PrettySafeLoader.construct_python_tuple)
doc = yaml.dump(tuple("foo bar baaz".split()))
print repr(doc)
thing = yaml.load(doc, Loader=PrettySafeLoader)
print thing
导致：
'!!python/tuple [foo, bar, baaz]\n'
('foo', 'bar', 'baaz')
请参阅下面的与SafeLoader和Loader类关联的构造函数。
>>> yaml.SafeLoader.yaml_constructors
{None: <unbound method SafeConstructor.construct_undefined>,
u'tag:yaml.org,2002:binary': <unbound method SafeConstructor.construct_yaml_binary>,
u'tag:yaml.org,2002:bool': <unbound method SafeConstructor.construct_yaml_bool>,
u'tag:yaml.org,2002:float': <unbound method SafeConstructor.construct_yaml_float>,
u'tag:yaml.org,2002:int': <unbound method SafeConstructor.construct_yaml_int>,
u'tag:yaml.org,2002:map': <unbound method SafeConstructor.construct_yaml_map>,
u'tag:yaml.org,2002:null': <unbound method SafeConstructor.construct_yaml_null>,
u'tag:yaml.org,2002:omap': <unbound method SafeConstructor.construct_yaml_omap>,
u'tag:yaml.org,2002:pairs': <unbound method SafeConstructor.construct_yaml_pairs>,
u'tag:yaml.org,2002:seq': <unbound method SafeConstructor.construct_yaml_seq>,
u'tag:yaml.org,2002:set': <unbound method SafeConstructor.construct_yaml_set>,
u'tag:yaml.org,2002:str': <unbound method SafeConstructor.construct_yaml_str>,
u'tag:yaml.org,2002:timestamp': <unbound method SafeConstructor.construct_yaml_timestamp>}
>>> yaml.Loader.yaml_constructors
{None: <unbound method SafeConstructor.construct_undefined>,
u'tag:yaml.org,2002:binary': <unbound method SafeConstructor.construct_yaml_binary>,
u'tag:yaml.org,2002:bool': <unbound method SafeConstructor.construct_yaml_bool>,
u'tag:yaml.org,2002:float': <unbound method SafeConstructor.construct_yaml_float>,
u'tag:yaml.org,2002:int': <unbound method SafeConstructor.construct_yaml_int>,
u'tag:yaml.org,2002:map': <unbound method SafeConstructor.construct_yaml_map>,
u'tag:yaml.org,2002:null': <unbound method SafeConstructor.construct_yaml_null>,
u'tag:yaml.org,2002:omap': <unbound method SafeConstructor.construct_yaml_omap>,
u'tag:yaml.org,2002:pairs': <unbound method SafeConstructor.construct_yaml_pairs>,
u'tag:yaml.org,2002:python/bool': <unbound method Constructor.construct_yaml_bool>,
u'tag:yaml.org,2002:python/complex': <unbound method Constructor.construct_python_complex>,
u'tag:yaml.org,2002:python/dict': <unbound method Constructor.construct_yaml_map>,
u'tag:yaml.org,2002:python/float': <unbound method Constructor.construct_yaml_float>,
u'tag:yaml.org,2002:python/int': <unbound method Constructor.construct_yaml_int>,
u'tag:yaml.org,2002:python/list': <unbound method Constructor.construct_yaml_seq>,
u'tag:yaml.org,2002:python/long': <unbound method Constructor.construct_python_long>,
u'tag:yaml.org,2002:python/none': <unbound method Constructor.construct_yaml_null>,
u'tag:yaml.org,2002:python/str': <unbound method Constructor.construct_python_str>,
u'tag:yaml.org,2002:python/tuple': <unbound method Constructor.construct_python_tuple>,
u'tag:yaml.org,2002:python/unicode': <unbound method Constructor.construct_python_unicode>,
u'tag:yaml.org,2002:seq': <unbound method SafeConstructor.construct_yaml_seq>,
u'tag:yaml.org,2002:set': <unbound method SafeConstructor.construct_yaml_set>,
u'tag:yaml.org,2002:str': <unbound method SafeConstructor.construct_yaml_str>,
u'tag:yaml.org,2002:timestamp': <unbound method SafeConstructor.construct_yaml_timestamp>}
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