Documentation for load() is wrong

The documentation has many instances of load being called with one argument, which is invalid usage since release 6.0. For instance, one example looks like this:

>>> stream = file('document.yaml', 'r')    # 'document.yaml' contains a single YAML document.
>>> yaml.load(stream)

This call of load does not work in release 6.0.

Also, the signature in the Reference section is incorrect. The signature is given as load(stream, Loader=Loader) but the correct signature is load(stream, Loader).

safe_load_all() raises ConstructorError where safe_load() does not.

Description

safe_load_all() raises yaml.constructor.ConstructorError for tag !include where safe_load() does not.

Steps to reproduce

Install Miniconda
Create conda environment:

...$ conda create -n foo python=3 PyYAML
...$ conda activate foo

Create file foo.py:

import yaml

# This works fine
try:
    yaml.safe_load(
        """
        includes:
          - !include some_file.yaml
        """
    )
except yaml.YAMLError as e:
    pass

# This does not
try:
    docs = yaml.safe_load_all(
        """
        includes:
          - !include some_file.yaml
        """
    )
except yaml.YAMLError as e:
    pass

for doc in docs:
    pass

4: Run: (foo) ...$ python foo.py

Error

Traceback (most recent call last):
  File "foo.py", line 25, in <module>
    for doc in docs:
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/__init__.py", line 130, in load_all
    yield loader.get_data()
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/constructor.py", line 37, in get_data
    return self.construct_document(self.get_node())
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/constructor.py", line 52, in construct_document
    for dummy in generator:
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/constructor.py", line 399, in construct_yaml_seq
    data.extend(self.construct_sequence(node))
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/constructor.py", line 121, in construct_sequence
    return [self.construct_object(child, deep=deep)
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/constructor.py", line 121, in <listcomp>
    return [self.construct_object(child, deep=deep)
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/constructor.py", line 92, in construct_object
    data = constructor(self, node)
  File "/home/moss/miniconda3/envs/test/lib/python3.8/site-packages/yaml/constructor.py", line 418, in construct_undefined
    raise ConstructorError(None, None,
yaml.constructor.ConstructorError: could not determine a constructor for the tag '!include'
  in "<unicode string>", line 3, column 13:
              - !include some_file.yaml
                ^

Clarify that load_all methods return a generator, not a sequence

The documentation for load_all and safe_load_all states (emphasis mine):

... returns a sequence of Python objects ...

In reality, those methods return a generator, which is not the same thing as a sequence. For example:

with open(filename) as f:
    docs = yaml.safe_load_all(f)
for d in docs:
    # do stuff

will raise ValueError: I/O operation on closed file. which if docs was really a sequence doesn't make sense.

(Moved from yaml/pyyaml#762)

error in representer.py

Hi,

I'm using pyyaml 5.4.1, installed from pypi, and came across the error below. Could you perhaps help me understand what goes wrong?

Many thanks in advance.

c:\users\gpipeleers.conda\envs\bp\lib\site-packages\yaml_init_.py in dump(data, stream, Dumper, **kwds)
288 If stream is None, return the produced string instead.
289 """
--> 290 return dump_all([data], stream, Dumper=Dumper, **kwds)
291
292 def safe_dump_all(documents, stream=None, **kwds):

c:\users\gpipeleers.conda\envs\bp\lib\site-packages\yaml_init_.py in dump_all(documents, stream, Dumper, default_style, default_flow_style, canonical, indent, width, allow_unicode, line_break, encoding, explicit_start, explicit_end, version, tags, sort_keys)
276 dumper.open()
277 for data in documents:
--> 278 dumper.represent(data)
279 dumper.close()
280 finally:

c:\users\gpipeleers.conda\envs\bp\lib\site-packages\yaml\representer.py in represent(self, data)
25
26 def represent(self, data):
---> 27 node = self.represent_data(data)
28 self.serialize(node)
29 self.represented_objects = {}