Improve typing and MIME hook API for inspector (#14342)

Fixes https://github.com/ipython/ipython/issues/14339

### Additions

Adds `InfoDict` type to improve the typing of `info()` result.

Adds missing `"subclasses"` to `info_fields` list (these were added to
the field list in https://github.com/ipython/ipython/pull/11486 but we
forgot to update `info_fields` variable at the time) - the newly added
`InfoDict` type will ensure that this won't happen again.

Adds `InspectorHookData` dataclass which is passed to the MIME hooks
which now should expect a single argument. Having a single dataclass
argument enables us to deprecate individual fields, or add new fields
without breaking the existing hooks. The old hooks will still work (if
any are out there since this mechanism got just added in the previous
point version).

### Deletions

A comment over `info_fields` gets deleted:
- Contrarily to the comment (which is getting deleted in this PR),
`info_fields` were not defining the order of display since at least 2015
(https://github.com/ipython/ipython/pull/7903 - I did not feel the need
to go further in the history to find when exactly it happened).
- Also contrarily to this comment, current Jupyter messaging spec does
not define the contents of `info_fields` (I guess this was lost during
IPython/Jupyter split), but the newly added `InfoDict` at least properly
annotates their type (if you know where I can find the old IPython
messaging spec with the descriptions I can add these as doc comments).

Unused `cast_unicode` import gets deleted. If someone imported it from
here... well they really should not have.

### Deprecations

- mime hooks taking two arguments (`obj, info`)

IPython/core/oinspect.py

@@ -1,1183 +1,1245 b''
 """Tools for inspecting Python objects.
 
 Uses syntax highlighting for presenting the various information elements.
 
 Similar in spirit to the inspect module, but all calls take a name argument to
 reference the name under which an object is being read.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 __all__ = ['Inspector','InspectColors']
 
 # stdlib modules
 from dataclasses import dataclass
 from inspect import signature
 from textwrap import dedent
 import ast
 import html
 import inspect
 import io as stdlib_io
 import linecache
 import os
 import types
 import warnings
 
-from typing import Any, Optional, Dict, Union, List, Tuple
-
-from typing import TypeAlias
+from typing import cast, Any, Optional, Dict, Union, List, TypedDict, TypeAlias, Tuple
 
 import traitlets
 
 # IPython's own
 from IPython.core import page
 from IPython.lib.pretty import pretty
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import PyColorize
 from IPython.utils import openpy
 from IPython.utils.dir2 import safe_hasattr
 from IPython.utils.path import compress_user
 from IPython.utils.text import indent
 from IPython.utils.wildcard import list_namespace
 from IPython.utils.wildcard import typestr2type
 from IPython.utils.coloransi import TermColors
-from IPython.utils.py3compat import cast_unicode
 from IPython.utils.colorable import Colorable
 from IPython.utils.decorators import undoc
 
 from pygments import highlight
 from pygments.lexers import PythonLexer
 from pygments.formatters import HtmlFormatter
 
 HOOK_NAME = "__custom_documentations__"
 
 
 UnformattedBundle: TypeAlias = Dict[str, List[Tuple[str, str]]]  # List of (title, body)
 Bundle: TypeAlias = Dict[str, str]
 
 
 @dataclass
 class OInfo:
     ismagic: bool
     isalias: bool
     found: bool
     namespace: Optional[str]
     parent: Any
     obj: Any
 
     def get(self, field):
         """Get a field from the object for backward compatibility with before 8.12
 
         see https://github.com/h5py/h5py/issues/2253
         """
         # We need to deprecate this at some point, but the warning will show in completion.
         # Let's comment this for now and uncomment end of 2023 ish
         #        warnings.warn(
         #            f"OInfo dataclass with fields access since IPython 8.12 please use OInfo.{field} instead."
         #            "OInfo used to be a dict but a dataclass provide static fields verification with mypy."
         #            "This warning and backward compatibility `get()` method were added in 8.13.",
         #            DeprecationWarning,
         #            stacklevel=2,
         #        )
         return getattr(self, field)
 
 
 def pylight(code):
     return highlight(code, PythonLexer(), HtmlFormatter(noclasses=True))
 
 # builtin docstrings to ignore
 _func_call_docstring = types.FunctionType.__call__.__doc__
 _object_init_docstring = object.__init__.__doc__
 _builtin_type_docstrings = {
     inspect.getdoc(t) for t in (types.ModuleType, types.MethodType,
                                 types.FunctionType, property)
 }
 
 _builtin_func_type = type(all)
 _builtin_meth_type = type(str.upper)  # Bound methods have the same type as builtin functions
 #****************************************************************************
 # Builtin color schemes
 
 Colors = TermColors  # just a shorthand
 
 InspectColors = PyColorize.ANSICodeColors
 
 #****************************************************************************
 # Auxiliary functions and objects
 
-# See the messaging spec for the definition of all these fields.  This list
-# effectively defines the order of display
-info_fields = ['type_name', 'base_class', 'string_form', 'namespace',
-               'length', 'file', 'definition', 'docstring', 'source',
-               'init_definition', 'class_docstring', 'init_docstring',
-               'call_def', 'call_docstring',
-               # These won't be printed but will be used to determine how to
-               # format the object
-               'ismagic', 'isalias', 'isclass', 'found', 'name'
-               ]
+
+class InfoDict(TypedDict):
+    type_name: Optional[str]
+    base_class: Optional[str]
+    string_form: Optional[str]
+    namespace: Optional[str]
+    length: Optional[str]
+    file: Optional[str]
+    definition: Optional[str]
+    docstring: Optional[str]
+    source: Optional[str]
+    init_definition: Optional[str]
+    class_docstring: Optional[str]
+    init_docstring: Optional[str]
+    call_def: Optional[str]
+    call_docstring: Optional[str]
+    subclasses: Optional[str]
+    # These won't be printed but will be used to determine how to
+    # format the object
+    ismagic: bool
+    isalias: bool
+    isclass: bool
+    found: bool
+    name: str
+
+
+info_fields = list(InfoDict.__annotations__.keys())
+
+
+@dataclass
+class InspectorHookData:
+    """Data passed to the mime hook"""
+
+    obj: Any
+    info: Optional[OInfo]
+    info_dict: InfoDict
+    detail_level: int
+    omit_sections: list[str]
 
 
+@undoc
 def object_info(**kw):
     """Make an object info dict with all fields present."""
-    infodict = {k:None for k in info_fields}
+    infodict = {k: None for k in info_fields}
     infodict.update(kw)
     return infodict
 
 
 def get_encoding(obj):
     """Get encoding for python source file defining obj
 
     Returns None if obj is not defined in a sourcefile.
     """
     ofile = find_file(obj)
     # run contents of file through pager starting at line where the object
     # is defined, as long as the file isn't binary and is actually on the
     # filesystem.
     if ofile is None:
         return None
     elif ofile.endswith(('.so', '.dll', '.pyd')):
         return None
     elif not os.path.isfile(ofile):
         return None
     else:
         # Print only text files, not extension binaries.  Note that
         # getsourcelines returns lineno with 1-offset and page() uses
         # 0-offset, so we must adjust.
         with stdlib_io.open(ofile, 'rb') as buffer:   # Tweaked to use io.open for Python 2
             encoding, _lines = openpy.detect_encoding(buffer.readline)
         return encoding
 
+
 def getdoc(obj) -> Union[str,None]:
     """Stable wrapper around inspect.getdoc.
 
     This can't crash because of attribute problems.
 
     It also attempts to call a getdoc() method on the given object.  This
     allows objects which provide their docstrings via non-standard mechanisms
     (like Pyro proxies) to still be inspected by ipython's ? system.
     """
     # Allow objects to offer customized documentation via a getdoc method:
     try:
         ds = obj.getdoc()
     except Exception:
         pass
     else:
         if isinstance(ds, str):
             return inspect.cleandoc(ds)
     docstr = inspect.getdoc(obj)
     return docstr
 
 
 def getsource(obj, oname='') -> Union[str,None]:
     """Wrapper around inspect.getsource.
 
     This can be modified by other projects to provide customized source
     extraction.
 
     Parameters
     ----------
     obj : object
         an object whose source code we will attempt to extract
     oname : str
         (optional) a name under which the object is known
 
     Returns
     -------
     src : unicode or None
 
     """
 
     if isinstance(obj, property):
         sources = []
         for attrname in ['fget', 'fset', 'fdel']:
             fn = getattr(obj, attrname)
             if fn is not None:
                 encoding = get_encoding(fn)
                 oname_prefix = ('%s.' % oname) if oname else ''
                 sources.append(''.join(('# ', oname_prefix, attrname)))
                 if inspect.isfunction(fn):
                     _src = getsource(fn)
                     if _src:
                         # assert _src is not None, "please mypy"
                         sources.append(dedent(_src))
                 else:
                     # Default str/repr only prints function name,
                     # pretty.pretty prints module name too.
                     sources.append(
                         '%s%s = %s\n' % (oname_prefix, attrname, pretty(fn))
                     )
         if sources:
             return '\n'.join(sources)
         else:
             return None
 
     else:
         # Get source for non-property objects.
 
         obj = _get_wrapped(obj)
 
         try:
             src = inspect.getsource(obj)
         except TypeError:
             # The object itself provided no meaningful source, try looking for
             # its class definition instead.
             try:
                 src = inspect.getsource(obj.__class__)
             except (OSError, TypeError):
                 return None
         except OSError:
             return None
 
         return src
 
 
 def is_simple_callable(obj):
     """True if obj is a function ()"""
     return (inspect.isfunction(obj) or inspect.ismethod(obj) or \
             isinstance(obj, _builtin_func_type) or isinstance(obj, _builtin_meth_type))
 
 @undoc
 def getargspec(obj):
     """Wrapper around :func:`inspect.getfullargspec`
 
     In addition to functions and methods, this can also handle objects with a
     ``__call__`` attribute.
 
     DEPRECATED: Deprecated since 7.10. Do not use, will be removed.
     """
 
     warnings.warn('`getargspec` function is deprecated as of IPython 7.10'
                   'and will be removed in future versions.', DeprecationWarning, stacklevel=2)
 
     if safe_hasattr(obj, '__call__') and not is_simple_callable(obj):
         obj = obj.__call__
 
     return inspect.getfullargspec(obj)
 
 @undoc
 def format_argspec(argspec):
     """Format argspect, convenience wrapper around inspect's.
 
     This takes a dict instead of ordered arguments and calls
     inspect.format_argspec with the arguments in the necessary order.
 
     DEPRECATED (since 7.10): Do not use; will be removed in future versions.
     """
     
     warnings.warn('`format_argspec` function is deprecated as of IPython 7.10'
                   'and will be removed in future versions.', DeprecationWarning, stacklevel=2)
 
 
     return inspect.formatargspec(argspec['args'], argspec['varargs'],
                                  argspec['varkw'], argspec['defaults'])
 
 @undoc
 def call_tip(oinfo, format_call=True):
     """DEPRECATED since 6.0. Extract call tip data from an oinfo dict."""
     warnings.warn(
         "`call_tip` function is deprecated as of IPython 6.0"
         "and will be removed in future versions.",
         DeprecationWarning,
         stacklevel=2,
     )
     # Get call definition
     argspec = oinfo.get('argspec')
     if argspec is None:
         call_line = None
     else:
         # Callable objects will have 'self' as their first argument, prune
         # it out if it's there for clarity (since users do *not* pass an
         # extra first argument explicitly).
         try:
             has_self = argspec['args'][0] == 'self'
         except (KeyError, IndexError):
             pass
         else:
             if has_self:
                 argspec['args'] = argspec['args'][1:]
 
         call_line = oinfo['name']+format_argspec(argspec)
 
     # Now get docstring.
     # The priority is: call docstring, constructor docstring, main one.
     doc = oinfo.get('call_docstring')
     if doc is None:
         doc = oinfo.get('init_docstring')
     if doc is None:
         doc = oinfo.get('docstring','')
 
     return call_line, doc
 
 
 def _get_wrapped(obj):
     """Get the original object if wrapped in one or more @decorators
 
     Some objects automatically construct similar objects on any unrecognised
     attribute access (e.g. unittest.mock.call). To protect against infinite loops,
     this will arbitrarily cut off after 100 levels of obj.__wrapped__
     attribute access. --TK, Jan 2016
     """
     orig_obj = obj
     i = 0
     while safe_hasattr(obj, '__wrapped__'):
         obj = obj.__wrapped__
         i += 1
         if i > 100:
             # __wrapped__ is probably a lie, so return the thing we started with
             return orig_obj
     return obj
 
 def find_file(obj) -> Optional[str]:
     """Find the absolute path to the file where an object was defined.
 
     This is essentially a robust wrapper around `inspect.getabsfile`.
 
     Returns None if no file can be found.
 
     Parameters
     ----------
     obj : any Python object
 
     Returns
     -------
     fname : str
         The absolute path to the file where the object was defined.
     """
     obj = _get_wrapped(obj)
 
     fname: Optional[str] = None
     try:
         fname = inspect.getabsfile(obj)
     except TypeError:
         # For an instance, the file that matters is where its class was
         # declared.
         try:
             fname = inspect.getabsfile(obj.__class__)
         except (OSError, TypeError):
             # Can happen for builtins
             pass
     except OSError:
         pass
 
     return fname
 
 
 def find_source_lines(obj):
     """Find the line number in a file where an object was defined.
 
     This is essentially a robust wrapper around `inspect.getsourcelines`.
 
     Returns None if no file can be found.
 
     Parameters
     ----------
     obj : any Python object
 
     Returns
     -------
     lineno : int
         The line number where the object definition starts.
     """
     obj = _get_wrapped(obj)
 
     try:
         lineno = inspect.getsourcelines(obj)[1]
     except TypeError:
         # For instances, try the class object like getsource() does
         try:
             lineno = inspect.getsourcelines(obj.__class__)[1]
         except (OSError, TypeError):
             return None
     except OSError:
         return None
 
     return lineno
 
 class Inspector(Colorable):
 
     mime_hooks = traitlets.Dict(
         config=True,
         help="dictionary of mime to callable to add informations into help mimebundle dict",
     ).tag(config=True)
 
     def __init__(
         self,
         color_table=InspectColors,
         code_color_table=PyColorize.ANSICodeColors,
         scheme=None,
         str_detail_level=0,
         parent=None,
         config=None,
     ):
         super(Inspector, self).__init__(parent=parent, config=config)
         self.color_table = color_table
         self.parser = PyColorize.Parser(out='str', parent=self, style=scheme)
         self.format = self.parser.format
         self.str_detail_level = str_detail_level
         self.set_active_scheme(scheme)
 
     def _getdef(self,obj,oname='') -> Union[str,None]:
         """Return the call signature for any callable object.
 
         If any exception is generated, None is returned instead and the
         exception is suppressed."""
         if not callable(obj):
             return None
         try:
             return _render_signature(signature(obj), oname)
         except:
             return None
 
     def __head(self,h) -> str:
         """Return a header string with proper colors."""
         return '%s%s%s' % (self.color_table.active_colors.header,h,
                            self.color_table.active_colors.normal)
 
     def set_active_scheme(self, scheme):
         if scheme is not None:
             self.color_table.set_active_scheme(scheme)
             self.parser.color_table.set_active_scheme(scheme)
 
     def noinfo(self, msg, oname):
         """Generic message when no information is found."""
         print('No %s found' % msg, end=' ')
         if oname:
             print('for %s' % oname)
         else:
             print()
 
     def pdef(self, obj, oname=''):
         """Print the call signature for any callable object.
 
         If the object is a class, print the constructor information."""
 
         if not callable(obj):
             print('Object is not callable.')
             return
 
         header = ''
 
         if inspect.isclass(obj):
             header = self.__head('Class constructor information:\n')
 
 
         output = self._getdef(obj,oname)
         if output is None:
             self.noinfo('definition header',oname)
         else:
             print(header,self.format(output), end=' ')
 
     # In Python 3, all classes are new-style, so they all have __init__.
     @skip_doctest
     def pdoc(self, obj, oname='', formatter=None):
         """Print the docstring for any object.
 
         Optional:
         -formatter: a function to run the docstring through for specially
         formatted docstrings.
 
         Examples
         --------
         In [1]: class NoInit:
            ...:     pass
 
         In [2]: class NoDoc:
            ...:     def __init__(self):
            ...:         pass
 
         In [3]: %pdoc NoDoc
         No documentation found for NoDoc
 
         In [4]: %pdoc NoInit
         No documentation found for NoInit
 
         In [5]: obj = NoInit()
 
         In [6]: %pdoc obj
         No documentation found for obj
 
         In [5]: obj2 = NoDoc()
 
         In [6]: %pdoc obj2
         No documentation found for obj2
         """
 
         head = self.__head  # For convenience
         lines = []
         ds = getdoc(obj)
         if formatter:
             ds = formatter(ds).get('plain/text', ds)
         if ds:
             lines.append(head("Class docstring:"))
             lines.append(indent(ds))
         if inspect.isclass(obj) and hasattr(obj, '__init__'):
             init_ds = getdoc(obj.__init__)
             if init_ds is not None:
                 lines.append(head("Init docstring:"))
                 lines.append(indent(init_ds))
         elif hasattr(obj,'__call__'):
             call_ds = getdoc(obj.__call__)
             if call_ds:
                 lines.append(head("Call docstring:"))
                 lines.append(indent(call_ds))
 
         if not lines:
             self.noinfo('documentation',oname)
         else:
             page.page('\n'.join(lines))
 
     def psource(self, obj, oname=''):
         """Print the source code for an object."""
 
         # Flush the source cache because inspect can return out-of-date source
         linecache.checkcache()
         try:
             src = getsource(obj, oname=oname)
         except Exception:
             src = None
 
         if src is None:
             self.noinfo('source', oname)
         else:
             page.page(self.format(src))
 
     def pfile(self, obj, oname=''):
         """Show the whole file where an object was defined."""
 
         lineno = find_source_lines(obj)
         if lineno is None:
             self.noinfo('file', oname)
             return
 
         ofile = find_file(obj)
         # run contents of file through pager starting at line where the object
         # is defined, as long as the file isn't binary and is actually on the
         # filesystem.
         if ofile.endswith(('.so', '.dll', '.pyd')):
             print('File %r is binary, not printing.' % ofile)
         elif not os.path.isfile(ofile):
             print('File %r does not exist, not printing.' % ofile)
         else:
             # Print only text files, not extension binaries.  Note that
             # getsourcelines returns lineno with 1-offset and page() uses
             # 0-offset, so we must adjust.
             page.page(self.format(openpy.read_py_file(ofile, skip_encoding_cookie=False)), lineno - 1)
 
 
     def _mime_format(self, text:str, formatter=None) -> dict:
         """Return a mime bundle representation of the input text.
 
         - if `formatter` is None, the returned mime bundle has
            a ``text/plain`` field, with the input text.
            a ``text/html`` field with a ``<pre>`` tag containing the input text.
 
         - if ``formatter`` is not None, it must be a callable transforming the
           input text into a mime bundle. Default values for ``text/plain`` and
           ``text/html`` representations are the ones described above.
 
         Note:
 
         Formatters returning strings are supported but this behavior is deprecated.
 
         """
         defaults = {
             "text/plain": text,
             "text/html": f"<pre>{html.escape(text)}</pre>",
         }
 
         if formatter is None:
             return defaults
         else:
             formatted = formatter(text)
 
             if not isinstance(formatted, dict):
                 # Handle the deprecated behavior of a formatter returning
                 # a string instead of a mime bundle.
                 return {"text/plain": formatted, "text/html": f"<pre>{formatted}</pre>"}
 
             else:
                 return dict(defaults, **formatted)
 
     def format_mime(self, bundle: UnformattedBundle) -> Bundle:
         """Format a mimebundle being created by _make_info_unformatted into a real mimebundle"""
         # Format text/plain mimetype
         assert isinstance(bundle["text/plain"], list)
         for item in bundle["text/plain"]:
             assert isinstance(item, tuple)
 
         new_b: Bundle = {}
         lines = []
         _len = max(len(h) for h, _ in bundle["text/plain"])
 
         for head, body in bundle["text/plain"]:
             body = body.strip("\n")
             delim = "\n" if "\n" in body else " "
             lines.append(
                 f"{self.__head(head+':')}{(_len - len(head))*' '}{delim}{body}"
             )
 
         new_b["text/plain"] = "\n".join(lines)
 
         if "text/html" in bundle:
             assert isinstance(bundle["text/html"], list)
             for item in bundle["text/html"]:
                 assert isinstance(item, tuple)
             # Format the text/html mimetype
             if isinstance(bundle["text/html"], (list, tuple)):
                 # bundle['text/html'] is a list of (head, formatted body) pairs
                 new_b["text/html"] = "\n".join(
                     (f"<h1>{head}</h1>\n{body}" for (head, body) in bundle["text/html"])
                 )
 
         for k in bundle.keys():
             if k in ("text/html", "text/plain"):
                 continue
             else:
                 new_b[k] = bundle[k]  # type:ignore
         return new_b
 
     def _append_info_field(
         self,
         bundle: UnformattedBundle,
         title: str,
         key: str,
         info,
         omit_sections,
         formatter,
     ):
         """Append an info value to the unformatted mimebundle being constructed by _make_info_unformatted"""
         if title in omit_sections or key in omit_sections:
             return
         field = info[key]
         if field is not None:
             formatted_field = self._mime_format(field, formatter)
             bundle["text/plain"].append((title, formatted_field["text/plain"]))
             bundle["text/html"].append((title, formatted_field["text/html"]))
 
     def _make_info_unformatted(
         self, obj, info, formatter, detail_level, omit_sections
     ) -> UnformattedBundle:
         """Assemble the mimebundle as unformatted lists of information"""
         bundle: UnformattedBundle = {
             "text/plain": [],
             "text/html": [],
         }
 
         # A convenience function to simplify calls below
         def append_field(
             bundle: UnformattedBundle, title: str, key: str, formatter=None
         ):
             self._append_info_field(
                 bundle,
                 title=title,
                 key=key,
                 info=info,
                 omit_sections=omit_sections,
                 formatter=formatter,
             )
 
         def code_formatter(text) -> Bundle:
             return {
                 'text/plain': self.format(text),
                 'text/html': pylight(text)
             }
 
         if info["isalias"]:
             append_field(bundle, "Repr", "string_form")
 
         elif info['ismagic']:
             if detail_level > 0:
                 append_field(bundle, "Source", "source", code_formatter)
             else:
                 append_field(bundle, "Docstring", "docstring", formatter)
             append_field(bundle, "File", "file")
 
         elif info['isclass'] or is_simple_callable(obj):
             # Functions, methods, classes
             append_field(bundle, "Signature", "definition", code_formatter)
             append_field(bundle, "Init signature", "init_definition", code_formatter)
             append_field(bundle, "Docstring", "docstring", formatter)
             if detail_level > 0 and info["source"]:
                 append_field(bundle, "Source", "source", code_formatter)
             else:
                 append_field(bundle, "Init docstring", "init_docstring", formatter)
 
             append_field(bundle, "File", "file")
             append_field(bundle, "Type", "type_name")
             append_field(bundle, "Subclasses", "subclasses")
 
         else:
             # General Python objects
             append_field(bundle, "Signature", "definition", code_formatter)
             append_field(bundle, "Call signature", "call_def", code_formatter)
             append_field(bundle, "Type", "type_name")
             append_field(bundle, "String form", "string_form")
 
             # Namespace
             if info["namespace"] != "Interactive":
                 append_field(bundle, "Namespace", "namespace")
 
             append_field(bundle, "Length", "length")
             append_field(bundle, "File", "file")
 
             # Source or docstring, depending on detail level and whether
             # source found.
             if detail_level > 0 and info["source"]:
                 append_field(bundle, "Source", "source", code_formatter)
             else:
                 append_field(bundle, "Docstring", "docstring", formatter)
 
             append_field(bundle, "Class docstring", "class_docstring", formatter)
             append_field(bundle, "Init docstring", "init_docstring", formatter)
             append_field(bundle, "Call docstring", "call_docstring", formatter)
         return bundle
 
 
     def _get_info(
         self,
         obj: Any,
         oname: str = "",
         formatter=None,
         info: Optional[OInfo] = None,
         detail_level=0,
         omit_sections=(),
     ) -> Bundle:
         """Retrieve an info dict and format it.
 
         Parameters
         ----------
         obj : any
             Object to inspect and return info from
         oname : str (default: ''):
             Name of the variable pointing to `obj`.
         formatter : callable
         info
             already computed information
         detail_level : integer
             Granularity of detail level, if set to 1, give more information.
         omit_sections : container[str]
             Titles or keys to omit from output (can be set, tuple, etc., anything supporting `in`)
         """
 
         info_dict = self.info(obj, oname=oname, info=info, detail_level=detail_level)
+
         bundle = self._make_info_unformatted(
             obj,
             info_dict,
             formatter,
             detail_level=detail_level,
             omit_sections=omit_sections,
         )
-        for key, hook in self.mime_hooks.items():
-            res = hook(obj, info)
-            if res is not None:
-                bundle[key] = res
+        if self.mime_hooks:
+            hook_data = InspectorHookData(
+                obj=obj,
+                info=info,
+                info_dict=info_dict,
+                detail_level=detail_level,
+                omit_sections=omit_sections,
+            )
+            for key, hook in self.mime_hooks.items():
+                required_parameters = [
+                    parameter
+                    for parameter in inspect.signature(hook).parameters.values()
+                    if parameter.default != inspect.Parameter.default
+                ]
+                if len(required_parameters) == 1:
+                    res = hook(hook_data)
+                else:
+                    warnings.warn(
+                        "MIME hook format changed in IPython 8.22; hooks should now accept"
+                        " a single parameter (InspectorHookData); support for hooks requiring"
+                        " two-parameters (obj and info) will be removed in a future version",
+                        DeprecationWarning,
+                        stacklevel=2,
+                    )
+                    res = hook(obj, info)
+                if res is not None:
+                    bundle[key] = res
         return self.format_mime(bundle)
 
     def pinfo(
         self,
         obj,
         oname="",
         formatter=None,
         info: Optional[OInfo] = None,
         detail_level=0,
         enable_html_pager=True,
         omit_sections=(),
     ):
         """Show detailed information about an object.
 
         Optional arguments:
 
         - oname: name of the variable pointing to the object.
 
         - formatter: callable (optional)
               A special formatter for docstrings.
 
               The formatter is a callable that takes a string as an input
               and returns either a formatted string or a mime type bundle
               in the form of a dictionary.
 
               Although the support of custom formatter returning a string
               instead of a mime type bundle is deprecated.
 
         - info: a structure with some information fields which may have been
           precomputed already.
 
         - detail_level: if set to 1, more information is given.
 
         - omit_sections: set of section keys and titles to omit
         """
         assert info is not None
         info_b: Bundle = self._get_info(
             obj, oname, formatter, info, detail_level, omit_sections=omit_sections
         )
         if not enable_html_pager:
             del info_b["text/html"]
         page.page(info_b)
 
     def _info(self, obj, oname="", info=None, detail_level=0):
         """
         Inspector.info() was likely improperly marked as deprecated
         while only a parameter was deprecated. We "un-deprecate" it.
         """
 
         warnings.warn(
             "The `Inspector.info()` method has been un-deprecated as of 8.0 "
             "and the `formatter=` keyword removed. `Inspector._info` is now "
             "an alias, and you can just call `.info()` directly.",
             DeprecationWarning,
             stacklevel=2,
         )
         return self.info(obj, oname=oname, info=info, detail_level=detail_level)
 
-    def info(self, obj, oname="", info=None, detail_level=0) -> Dict[str, Any]:
+    def info(self, obj, oname="", info=None, detail_level=0) -> InfoDict:
         """Compute a dict with detailed information about an object.
 
         Parameters
         ----------
         obj : any
             An object to find information about
         oname : str (default: '')
             Name of the variable pointing to `obj`.
         info : (default: None)
             A struct (dict like with attr access) with some information fields
             which may have been precomputed already.
         detail_level : int (default:0)
             If set to 1, more information is given.
 
         Returns
         -------
-        An object info dict with known fields from `info_fields`. Keys are
-        strings, values are string or None.
+        An object info dict with known fields from `info_fields` (see `InfoDict`).
         """
 
         if info is None:
             ismagic = False
             isalias = False
             ospace = ''
         else:
             ismagic = info.ismagic
             isalias = info.isalias
             ospace = info.namespace
 
         # Get docstring, special-casing aliases:
         att_name = oname.split(".")[-1]
         parents_docs = None
         prelude = ""
         if info and info.parent is not None and hasattr(info.parent, HOOK_NAME):
             parents_docs_dict = getattr(info.parent, HOOK_NAME)
             parents_docs = parents_docs_dict.get(att_name, None)
-        out = dict(
-            name=oname, found=True, isalias=isalias, ismagic=ismagic, subclasses=None
+        out: InfoDict = cast(
+            InfoDict,
+            {
+                **{field: None for field in info_fields},
+                **{
+                    "name": oname,
+                    "found": True,
+                    "isalias": isalias,
+                    "ismagic": ismagic,
+                    "subclasses": None,
+                },
+            },
         )
 
         if parents_docs:
             ds = parents_docs
         elif isalias:
             if not callable(obj):
                 try:
                     ds = "Alias to the system command:\n  %s" % obj[1]
                 except:
                     ds = "Alias: " + str(obj)
             else:
                 ds = "Alias to " + str(obj)
                 if obj.__doc__:
                     ds += "\nDocstring:\n" + obj.__doc__
         else:
             ds_or_None = getdoc(obj)
             if ds_or_None is None:
                 ds = '<no docstring>'
             else:
                 ds = ds_or_None
 
         ds = prelude + ds
 
         # store output in a dict, we initialize it here and fill it as we go
 
         string_max = 200 # max size of strings to show (snipped if longer)
         shalf = int((string_max - 5) / 2)
 
         if ismagic:
             out['type_name'] = 'Magic function'
         elif isalias:
             out['type_name'] = 'System alias'
         else:
             out['type_name'] = type(obj).__name__
 
         try:
             bclass = obj.__class__
             out['base_class'] = str(bclass)
         except:
             pass
 
         # String form, but snip if too long in ? form (full in ??)
         if detail_level >= self.str_detail_level:
             try:
                 ostr = str(obj)
-                str_head = 'string_form'
-                if not detail_level and len(ostr)>string_max:
+                if not detail_level and len(ostr) > string_max:
                     ostr = ostr[:shalf] + ' <...> ' + ostr[-shalf:]
-                    ostr = ("\n" + " " * len(str_head.expandtabs())).\
-                            join(q.strip() for q in ostr.split("\n"))
-                out[str_head] = ostr
+                    # TODO: `'string_form'.expandtabs()` seems wrong, but
+                    # it was (nearly) like this since the first commit ever.
+                    ostr = ("\n" + " " * len("string_form".expandtabs())).join(
+                        q.strip() for q in ostr.split("\n")
+                    )
+                out["string_form"] = ostr
             except:
                 pass
 
         if ospace:
             out['namespace'] = ospace
 
         # Length (for strings and lists)
         try:
             out['length'] = str(len(obj))
         except Exception:
             pass
 
         # Filename where object was defined
         binary_file = False
         fname = find_file(obj)
         if fname is None:
             # if anything goes wrong, we don't want to show source, so it's as
             # if the file was binary
             binary_file = True
         else:
             if fname.endswith(('.so', '.dll', '.pyd')):
                 binary_file = True
             elif fname.endswith('<string>'):
                 fname = 'Dynamically generated function. No source code available.'
             out['file'] = compress_user(fname)
 
         # Original source code for a callable, class or property.
         if detail_level:
             # Flush the source cache because inspect can return out-of-date
             # source
             linecache.checkcache()
             try:
                 if isinstance(obj, property) or not binary_file:
                     src = getsource(obj, oname)
                     if src is not None:
                         src = src.rstrip()
                     out['source'] = src
 
             except Exception:
                 pass
 
         # Add docstring only if no source is to be shown (avoid repetitions).
         if ds and not self._source_contains_docstring(out.get('source'), ds):
             out['docstring'] = ds
 
         # Constructor docstring for classes
         if inspect.isclass(obj):
             out['isclass'] = True
 
             # get the init signature:
             try:
                 init_def = self._getdef(obj, oname)
             except AttributeError:
                 init_def = None
 
             # get the __init__ docstring
             try:
                 obj_init = obj.__init__
             except AttributeError:
                 init_ds = None
             else:
                 if init_def is None:
                     # Get signature from init if top-level sig failed.
                     # Can happen for built-in types (list, etc.).
                     try:
                         init_def = self._getdef(obj_init, oname)
                     except AttributeError:
                         pass
                 init_ds = getdoc(obj_init)
                 # Skip Python's auto-generated docstrings
                 if init_ds == _object_init_docstring:
                     init_ds = None
 
             if init_def:
                 out['init_definition'] = init_def
 
             if init_ds:
                 out['init_docstring'] = init_ds
 
             names = [sub.__name__ for sub in type.__subclasses__(obj)]
             if len(names) < 10:
                 all_names = ', '.join(names)
             else:
                 all_names = ', '.join(names[:10]+['...'])
             out['subclasses'] = all_names
         # and class docstring for instances:
         else:
             # reconstruct the function definition and print it:
             defln = self._getdef(obj, oname)
             if defln:
                 out['definition'] = defln
 
             # First, check whether the instance docstring is identical to the
             # class one, and print it separately if they don't coincide.  In
             # most cases they will, but it's nice to print all the info for
             # objects which use instance-customized docstrings.
             if ds:
                 try:
                     cls = getattr(obj,'__class__')
                 except:
                     class_ds = None
                 else:
                     class_ds = getdoc(cls)
                 # Skip Python's auto-generated docstrings
                 if class_ds in _builtin_type_docstrings:
                     class_ds = None
                 if class_ds and ds != class_ds:
                     out['class_docstring'] = class_ds
 
             # Next, try to show constructor docstrings
             try:
                 init_ds = getdoc(obj.__init__)
                 # Skip Python's auto-generated docstrings
                 if init_ds == _object_init_docstring:
                     init_ds = None
             except AttributeError:
                 init_ds = None
             if init_ds:
                 out['init_docstring'] = init_ds
 
             # Call form docstring for callable instances
             if safe_hasattr(obj, '__call__') and not is_simple_callable(obj):
                 call_def = self._getdef(obj.__call__, oname)
                 if call_def and (call_def != out.get('definition')):
                     # it may never be the case that call def and definition differ,
                     # but don't include the same signature twice
                     out['call_def'] = call_def
                 call_ds = getdoc(obj.__call__)
                 # Skip Python's auto-generated docstrings
                 if call_ds == _func_call_docstring:
                     call_ds = None
                 if call_ds:
                     out['call_docstring'] = call_ds
 
-        return object_info(**out)
+        return out
 
     @staticmethod
     def _source_contains_docstring(src, doc):
         """
         Check whether the source *src* contains the docstring *doc*.
 
         This is is helper function to skip displaying the docstring if the
         source already contains it, avoiding repetition of information.
         """
         try:
             (def_node,) = ast.parse(dedent(src)).body
             return ast.get_docstring(def_node) == doc  # type: ignore[arg-type]
         except Exception:
             # The source can become invalid or even non-existent (because it
             # is re-fetched from the source file) so the above code fail in
             # arbitrary ways.
             return False
 
     def psearch(self,pattern,ns_table,ns_search=[],
                 ignore_case=False,show_all=False, *, list_types=False):
         """Search namespaces with wildcards for objects.
 
         Arguments:
 
         - pattern: string containing shell-like wildcards to use in namespace
           searches and optionally a type specification to narrow the search to
           objects of that type.
 
         - ns_table: dict of name->namespaces for search.
 
         Optional arguments:
 
           - ns_search: list of namespace names to include in search.
 
           - ignore_case(False): make the search case-insensitive.
 
           - show_all(False): show all names, including those starting with
             underscores.
 
           - list_types(False): list all available object types for object matching.
         """
         #print 'ps pattern:<%r>' % pattern # dbg
 
         # defaults
         type_pattern = 'all'
         filter = ''
 
         # list all object types
         if list_types:
             page.page('\n'.join(sorted(typestr2type)))
             return
 
         cmds = pattern.split()
         len_cmds  =  len(cmds)
         if len_cmds == 1:
             # Only filter pattern given
             filter = cmds[0]
         elif len_cmds == 2:
             # Both filter and type specified
             filter,type_pattern = cmds
         else:
             raise ValueError('invalid argument string for psearch: <%s>' %
                              pattern)
 
         # filter search namespaces
         for name in ns_search:
             if name not in ns_table:
                 raise ValueError('invalid namespace <%s>. Valid names: %s' %
                                  (name,ns_table.keys()))
 
         #print 'type_pattern:',type_pattern # dbg
         search_result, namespaces_seen = set(), set()
         for ns_name in ns_search:
             ns = ns_table[ns_name]
             # Normally, locals and globals are the same, so we just check one.
             if id(ns) in namespaces_seen:
                 continue
             namespaces_seen.add(id(ns))
             tmp_res = list_namespace(ns, type_pattern, filter,
                                     ignore_case=ignore_case, show_all=show_all)
             search_result.update(tmp_res)
 
         page.page('\n'.join(sorted(search_result)))
 
 
 def _render_signature(obj_signature, obj_name) -> str:
     """
     This was mostly taken from inspect.Signature.__str__.
     Look there for the comments.
     The only change is to add linebreaks when this gets too long.
     """
     result = []
     pos_only = False
     kw_only = True
     for param in obj_signature.parameters.values():
         if param.kind == inspect.Parameter.POSITIONAL_ONLY:
             pos_only = True
         elif pos_only:
             result.append('/')
             pos_only = False
 
         if param.kind == inspect.Parameter.VAR_POSITIONAL:
             kw_only = False
         elif param.kind == inspect.Parameter.KEYWORD_ONLY and kw_only:
             result.append('*')
             kw_only = False
 
         result.append(str(param))
 
     if pos_only:
         result.append('/')
 
     # add up name, parameters, braces (2), and commas
     if len(obj_name) + sum(len(r) + 2 for r in result) > 75:
         # This doesn’t fit behind “Signature: ” in an inspect window.
         rendered = '{}(\n{})'.format(obj_name, ''.join(
             '    {},\n'.format(r) for r in result)
         )
     else:
         rendered = '{}({})'.format(obj_name, ', '.join(result))
 
     if obj_signature.return_annotation is not inspect._empty:
         anno = inspect.formatannotation(obj_signature.return_annotation)
         rendered += ' -> {}'.format(anno)
 
     return rendered