Add type annotations to _registry.py

Description

Add type annotations to _registry.py so that they will pass mypy
--strict.

Comment

I was reading the code and felt that this module would be easier to
understand with type annotations. Therefore, I went ahead and added the
annotations.

The idea with this PR is to start small to see if we can align on _how_
to annotate types. I've seen people in the past disagree on how strictly
to annotate the code base, so before spending too much time on this, I
wanted to check if you agree, Ross.

Most of the added types should be straightforward. Some notes on the
non-trivial changes:

- I made no assumption about the fn passed to register_model, but maybe
  the type could be stricter. Are all models nn.Modules?
- If I'm not mistaken, the type hint for get_arch_name was incorrect
- I had to add a # type: ignore to model.__all__ = ...
- I made some minor code changes to list_models to facilitate the
  typing. I think the changes should not affect the logic of the function.
- I removed list from list(sorted(...)) because sorted returns always a
  list.

timm/models/_pretrained.py

@@ -93,7 +93,7 @@ class DefaultCfg:
         return tag, self.cfgs[tag]
 
 
-def split_model_name_tag(model_name: str, no_tag=''):
+def split_model_name_tag(model_name: str, no_tag: str = '') -> Tuple[str, str]:
     model_name, *tag_list = model_name.split('.', 1)
     tag = tag_list[0] if tag_list else no_tag
     return model_name, tag

timm/models/_registry.py

@@ -8,7 +8,7 @@ import sys
 from collections import defaultdict, deque
 from copy import deepcopy
 from dataclasses import replace
-from typing import List, Optional, Union, Tuple
+from typing import Any, Callable, Dict, Iterable, List, Optional, Set, Sequence, Union, Tuple
 
 from ._pretrained import PretrainedCfg, DefaultCfg, split_model_name_tag
 
@@ -16,20 +16,20 @@ __all__ = [
     'list_models', 'list_pretrained', 'is_model', 'model_entrypoint', 'list_modules', 'is_model_in_modules',
     'get_pretrained_cfg_value', 'is_model_pretrained', 'get_arch_name']
 
-_module_to_models = defaultdict(set)  # dict of sets to check membership of model in module
-_model_to_module = {}  # mapping of model names to module names
-_model_entrypoints = {}  # mapping of model names to architecture entrypoint fns
-_model_has_pretrained = set()  # set of model names that have pretrained weight url present
-_model_default_cfgs = dict()  # central repo for model arch -> default cfg objects
-_model_pretrained_cfgs = dict()  # central repo for model arch.tag -> pretrained cfgs
-_model_with_tags = defaultdict(list)  # shortcut to map each model arch to all model + tag names
+_module_to_models: Dict[str, Set[str]] = defaultdict(set)  # dict of sets to check membership of model in module
+_model_to_module: Dict[str, str] = {}  # mapping of model names to module names
+_model_entrypoints: Dict[str, Callable[..., Any]] = {}  # mapping of model names to architecture entrypoint fns
+_model_has_pretrained: Set[str] = set()  # set of model names that have pretrained weight url present
+_model_default_cfgs: Dict[str, PretrainedCfg] = {}  # central repo for model arch -> default cfg objects
+_model_pretrained_cfgs: Dict[str, PretrainedCfg] = {}  # central repo for model arch.tag -> pretrained cfgs
+_model_with_tags: Dict[str, List[str]] = defaultdict(list)  # shortcut to map each model arch to all model + tag names
 
 
-def get_arch_name(model_name: str) -> Tuple[str, Optional[str]]:
+def get_arch_name(model_name: str) -> str:
     return split_model_name_tag(model_name)[0]
 
 
-def register_model(fn):
+def register_model(fn: Callable[..., Any]) -> Callable[..., Any]:
     # lookup containing module
     mod = sys.modules[fn.__module__]
     module_name_split = fn.__module__.split('.')
@@ -40,7 +40,7 @@ def register_model(fn):
     if hasattr(mod, '__all__'):
         mod.__all__.append(model_name)
     else:
-        mod.__all__ = [model_name]
+        mod.__all__ = [model_name]  # type: ignore
 
     # add entries to registry dict/sets
     _model_entrypoints[model_name] = fn
@@ -87,28 +87,33 @@ def register_model(fn):
     return fn
 
 
-def _natural_key(string_):
+def _natural_key(string_: str) -> List[Union[int, str]]:
+    """See https://blog.codinghorror.com/sorting-for-humans-natural-sort-order/"""
     return [int(s) if s.isdigit() else s for s in re.split(r'(\d+)', string_.lower())]
 
 
 def list_models(
         filter: Union[str, List[str]] = '',
         module: str = '',
-        pretrained=False,
-        exclude_filters: str = '',
+        pretrained: bool = False,
+        exclude_filters: Union[str, List[str]] = '',
         name_matches_cfg: bool = False,
         include_tags: Optional[bool] = None,
-):
+) -> List[str]:
     """ Return list of available model names, sorted alphabetically
 
     Args:
-        filter (str) - Wildcard filter string that works with fnmatch
-        module (str) - Limit model selection to a specific submodule (ie 'vision_transformer')
-        pretrained (bool) - Include only models with valid pretrained weights if True
-        exclude_filters (str or list[str]) - Wildcard filters to exclude models after including them with filter
-        name_matches_cfg (bool) - Include only models w/ model_name matching default_cfg name (excludes some aliases)
-        include_tags (Optional[boo]) - Include pretrained tags in model names (model.tag). If None, defaults
+        filter - Wildcard filter string that works with fnmatch
+        module - Limit model selection to a specific submodule (ie 'vision_transformer')
+        pretrained - Include only models with valid pretrained weights if True
+        exclude_filters - Wildcard filters to exclude models after including them with filter
+        name_matches_cfg - Include only models w/ model_name matching default_cfg name (excludes some aliases)
+        include_tags - Include pretrained tags in model names (model.tag). If None, defaults
             set to True when pretrained=True else False (default: None)
+
+    Returns:
+        models - The sorted list of models
+
     Example:
         model_list('gluon_resnet*') -- returns all models starting with 'gluon_resnet'
         model_list('*resnext*, 'resnet') -- returns all models with 'resnext' in 'resnet' module
@@ -118,7 +123,7 @@ def list_models(
         include_tags = pretrained
 
     if module:
-        all_models = list(_module_to_models[module])
+        all_models: Iterable[str] = list(_module_to_models[module])
     else:
         all_models = _model_entrypoints.keys()
 
@@ -130,14 +135,14 @@ def list_models(
         all_models = models_with_tags
 
     if filter:
-        models = []
+        models: Set[str] = set()
         include_filters = filter if isinstance(filter, (tuple, list)) else [filter]
         for f in include_filters:
             include_models = fnmatch.filter(all_models, f)  # include these models
             if len(include_models):
-                models = set(models).union(include_models)
+                models = models.union(include_models)
     else:
-        models = all_models
+        models = set(all_models)
 
     if exclude_filters:
         if not isinstance(exclude_filters, (tuple, list)):
@@ -145,7 +150,7 @@ def list_models(
         for xf in exclude_filters:
             exclude_models = fnmatch.filter(models, xf)  # exclude these models
             if len(exclude_models):
-                models = set(models).difference(exclude_models)
+                models = models.difference(exclude_models)
 
     if pretrained:
         models = _model_has_pretrained.intersection(models)
@@ -153,13 +158,13 @@ def list_models(
     if name_matches_cfg:
         models = set(_model_pretrained_cfgs).intersection(models)
 
-    return list(sorted(models, key=_natural_key))
+    return sorted(models, key=_natural_key)
 
 
 def list_pretrained(
         filter: Union[str, List[str]] = '',
         exclude_filters: str = '',
-):
+) -> List[str]:
     return list_models(
         filter=filter,
         pretrained=True,
@@ -168,14 +173,14 @@ def list_pretrained(
     )
 
 
-def is_model(model_name):
+def is_model(model_name: str) -> bool:
     """ Check if a model name exists
     """
     arch_name = get_arch_name(model_name)
     return arch_name in _model_entrypoints
 
 
-def model_entrypoint(model_name, module_filter: Optional[str] = None):
+def model_entrypoint(model_name: str, module_filter: Optional[str] = None) -> Callable[..., Any]:
     """Fetch a model entrypoint for specified model name
     """
     arch_name = get_arch_name(model_name)
@@ -184,29 +189,32 @@ def model_entrypoint(model_name, module_filter: Optional[str] = None):
     return _model_entrypoints[arch_name]
 
 
-def list_modules():
+def list_modules() -> List[str]:
     """ Return list of module names that contain models / model entrypoints
     """
     modules = _module_to_models.keys()
-    return list(sorted(modules))
+    return sorted(modules)
 
 
-def is_model_in_modules(model_name, module_names):
+def is_model_in_modules(
+        model_name: str, module_names: Union[Tuple[str, ...], List[str], Set[str]]
+) -> bool:
     """Check if a model exists within a subset of modules
+
     Args:
-        model_name (str) - name of model to check
-        module_names (tuple, list, set) - names of modules to search in
+        model_name - name of model to check
+        module_names - names of modules to search in
     """
     arch_name = get_arch_name(model_name)
     assert isinstance(module_names, (tuple, list, set))
     return any(arch_name in _module_to_models[n] for n in module_names)
 
 
-def is_model_pretrained(model_name):
+def is_model_pretrained(model_name: str) -> bool:
     return model_name in _model_has_pretrained
 
 
-def get_pretrained_cfg(model_name, allow_unregistered=True):
+def get_pretrained_cfg(model_name: str, allow_unregistered: bool = True) -> Optional[PretrainedCfg]:
     if model_name in _model_pretrained_cfgs:
         return deepcopy(_model_pretrained_cfgs[model_name])
     arch_name, tag = split_model_name_tag(model_name)
@@ -219,7 +227,7 @@ def get_pretrained_cfg(model_name, allow_unregistered=True):
     raise RuntimeError(f'Model architecture ({arch_name}) has no pretrained cfg registered.')
 
 
-def get_pretrained_cfg_value(model_name, cfg_key):
+def get_pretrained_cfg_value(model_name: str, cfg_key: str) -> Optional[Any]:
     """ Get a specific model default_cfg value by key. None if key doesn't exist.
     """
     cfg = get_pretrained_cfg(model_name, allow_unregistered=False)