Loader dumper objects api #563

ingydotnet · 2021-09-23T19:06:32Z

Depends on #561

perlpunk · 2021-09-24T20:50:06Z

lib/yaml/constructor.py

@@ -76,9 +81,23 @@ def construct_object(self, node, deep=False):
        self.recursive_objects[node] = None
        constructor = None
        tag_suffix = None
-        if node.tag in self.yaml_constructors:
+
+        if (hasattr(self, '_yaml_constructors') and


I would write a wrapper for this. Not sure about a good name.

Do you plan to add the resolvers and representers in this PR, too?

perlpunk · 2021-09-24T20:56:23Z

lib/yaml/constructor.py

+
+        if (hasattr(self, '_yaml_constructors') and
+            node.tag in self._yaml_constructors and
+            self._yaml_constructors[node.tag] is not None


Could be easier to delete the constructor when doing add_constructor(tag, None)? Then this check wouldn't be necessary

perlpunk · 2021-09-24T20:59:09Z

lib/yaml/constructor.py

+
+        if constructor is None and hasattr(self, '_yaml_constructors'):
+            for tag_prefix in self._yaml_multi_constructors:
+                if tag_prefix is not None and node.tag.startswith(tag_prefix):


The None part of the multi_constructors below is not yet supported

perlpunk

Maybe it would be clearer to do something like this at the start of construct_object:

if self.is_instance_based():
    constructors = self._yaml_constructors
    multi_constructors = self._yaml_multi_constructors
else:
    constructors = self.yaml_constructors
    multi_constructors = self.yaml_multi_constructors

Then later code doesn't need to be duplicated

Thom1729 · 2021-09-24T21:07:03Z

lib/yaml/__init__.py

+#         loader = Loader.get('cls')(stream)
+
+    else:
+        raise AssertionError("Unsupported type for Loader=")


Should be TypeError.

Thom1729 · 2021-09-24T21:08:03Z

lib/yaml/__init__.py

+
+    if loader.stream is None:
+        if stream is None:
+            raise AssertionError("load() requires stream=...")


Should be TypeError.

perlpunk · 2021-09-24T21:37:20Z

One thing which is not clear from the example is an important design question:
The current PR looks into the instance based constructors (if it is an instance), and if it doesn't find the tag there, it goes on to search in the class based constructors.
Meaning, doing

l1 = yaml.SafeLoader()
yaml.add_constructor('!dice', dice_constructor, Loader=yaml.SafeLoader)

will still result in finding a constructor for !dice when using l1

My proposal would be to only lookup in one or the other - either instance or class based.
After all we want to get away from the class based global-like thing, and any new stuff would only be supported by the instance API.

ingydotnet · 2021-09-25T12:06:29Z

One thing which is not clear from the example is an important design question:
The current PR looks into the instance based constructors (if it is an instance), and if it doesn't find the tag there, it goes on to search in the class based constructors.
Meaning, doing
l1 = yaml.SafeLoader()
yaml.add_constructor('!dice', dice_constructor, Loader=yaml.SafeLoader)
will still result in finding a constructor for !dice when using l1

My proposal would be to only lookup in one or the other - either instance or class based.
After all we want to get away from the class based global-like thing, and any new stuff would only be supported by the instance API.

Good point but your instance needs to at least copy over the default class constructors. iow, integers still need to work.

I still have a lot to finish up on this PR. Should have something reviewable by Monday.

lib/yaml/__init__.py

perlpunk · 2021-09-25T14:58:08Z

Good point but your instance needs to at least copy over the default class constructors.

of course.

iow, integers still need to work.

integers?

instead of just Loader* classes All existing PyYAML usage should not be affected.

ingydotnet added this to Review in PyYAML 6.0 Release Planning Sep 23, 2021

ingydotnet moved this from Review to Abandoned in PyYAML 6.0 Release Planning Sep 23, 2021

ingydotnet force-pushed the release/6.0 branch from 1b2f534 to 8f3f979 Compare September 23, 2021 21:47

ingydotnet force-pushed the loader-dumper-objects-api branch 2 times, most recently from 682fbb2 to bfc4e97 Compare September 24, 2021 20:40

perlpunk reviewed Sep 24, 2021

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Thom1729 reviewed Sep 24, 2021

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perlpunk reviewed Sep 25, 2021

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lib/yaml/__init__.py Outdated Show resolved Hide resolved

ingydotnet force-pushed the loader-dumper-objects-api branch from bfc4e97 to da67d4b Compare September 25, 2021 16:34

ingydotnet added 2 commits September 26, 2021 21:51

Change yaml.load* methods to accept a Loader* instance

c468e52

instead of just Loader* classes All existing PyYAML usage should not be affected.

Example script

8fb8979

ingydotnet force-pushed the loader-dumper-objects-api branch from 2495a71 to 8fb8979 Compare September 27, 2021 01:54

ingydotnet self-assigned this Jan 29, 2022

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Loader dumper objects api #563

Loader dumper objects api #563

ingydotnet commented Sep 23, 2021 •

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Loader dumper objects api #563

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Loader dumper objects api #563

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