Adding upstream version 0.91.0.upstream/0.91.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 101 insertions, 0 deletions

diff --git a/_doc/dumpcls.rst b/_doc/dumpcls.rst
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+
+**********************
+Dumping Python classes
+**********************
+
+Only ``yaml = YAML(typ='unsafe')`` loads and dumps Python objects out-of-the-box. And
+since it loads **any** Python object, this can be unsafe.
+
+If you have instances of some class(es) that you want to dump or load, it is
+easy to allow the YAML instance to do that explicitly. You can either register the
+class with the ``YAML`` instance or decorate the class.
+
+Registering is done with ``YAML.register_class()``::
+
+    import sys
+    import ruyaml
+
+
+    class User:
+        def __init__(self, name, age):
+            self.name = name
+            self.age = age
+
+
+    yaml = ruyaml.YAML()
+    yaml.register_class(User)
+    yaml.dump([User('Anthon', 18)], sys.stdout)
+
+which gives as output::
+
+    - !User
+      name: Anthon
+      age: 18
+
+The tag ``!User`` originates from the name of the class.
+
+You can specify a different tag by adding the attribute ``yaml_tag``, and
+explicitly specify dump and/or load *classmethods* which have to be called
+``from_yaml`` resp. ``from_yaml``::
+
+    import sys
+    import ruyaml
+
+
+    class User:
+        yaml_tag = u'!user'
+
+        def __init__(self, name, age):
+            self.name = name
+            self.age = age
+
+        @classmethod
+        def to_yaml(cls, representer, node):
+            return representer.represent_scalar(cls.yaml_tag,
+                                                u'{.name}-{.age}'.format(node, node))
+
+        @classmethod
+        def from_yaml(cls, constructor, node):
+            return cls(*node.value.split('-'))
+
+
+    yaml = ruyaml.YAML()
+    yaml.register_class(User)
+    yaml.dump([User('Anthon', 18)], sys.stdout)
+
+which gives as output::
+
+    - !user Anthon-18
+
+
+When using the decorator, which takes the ``YAML()`` instance as a parameter,
+the ``yaml = YAML()`` line needs to be moved up in the file::
+
+    import sys
+    from ruyaml import YAML, yaml_object
+
+    yaml = YAML()
+
+
+    @yaml_object(yaml)
+    class User:
+        yaml_tag = u'!user'
+
+        def __init__(self, name, age):
+            self.name = name
+            self.age = age
+
+        @classmethod
+        def to_yaml(cls, representer, node):
+            return representer.represent_scalar(cls.yaml_tag,
+                                                u'{.name}-{.age}'.format(node, node))
+
+        @classmethod
+        def from_yaml(cls, constructor, node):
+            return cls(*node.value.split('-'))
+
+
+    yaml.dump([User('Anthon', 18)], sys.stdout)
+
+The ``yaml_tag``, ``from_yaml`` and ``to_yaml`` work in the same way as when using
+``.register_class()``.