Move misc minor utils to a separate module

1 files changed, 48 insertions, 0 deletions

diff --git a/requests_cache/_utils.py b/requests_cache/_utils.py
new file mode 100644
index 0000000..b3dfaee
--- /dev/null
+++ b/requests_cache/_utils.py
@@ -0,0 +1,48 @@
+"""Miscellaneous minor utility functions that don't really belong anywhere else"""
+from inspect import signature
+from logging import getLogger
+from typing import Any, Callable, Dict, Iterable, Iterator, List
+
+logger = getLogger('requests_cache')
+
+
+def chunkify(iterable: Iterable, max_size: int) -> Iterator[List]:
+    """Split an iterable into chunks of a max size"""
+    iterable = list(iterable)
+    for index in range(0, len(iterable), max_size):
+        yield iterable[index : index + max_size]
+
+
+def coalesce(*values: Any, default=None) -> Any:
+    """Get the first non-``None`` value in a list of values"""
+    return next((v for v in values if v is not None), default)
+
+
+def get_placeholder_class(original_exception: Exception = None):
+    """Create a placeholder type for a class that does not have dependencies installed.
+    This allows delaying ImportErrors until init time, rather than at import time.
+    """
+    msg = 'Dependencies are not installed for this feature'
+
+    def _log_error():
+        logger.error(msg)
+        raise original_exception or ImportError(msg)
+
+    class Placeholder:
+        def __init__(self, *args, **kwargs):
+            _log_error()
+
+        def __getattr__(self, *args, **kwargs):
+            _log_error()
+
+        def dumps(self, *args, **kwargs):
+            _log_error()
+
+    return Placeholder
+
+
+def get_valid_kwargs(func: Callable, kwargs: Dict, extras: Iterable[str] = None) -> Dict:
+    """Get the subset of non-None ``kwargs`` that are valid params for ``func``"""
+    params = list(signature(func).parameters)
+    params.extend(extras or [])
+    return {k: v for k, v in kwargs.items() if k in params and v is not None}