Switch build backend to Hatchling (#3233)

[etc/vim.git] / src / black / cache.py

diff --git a/src/black/cache.py b/src/black/cache.py
index bca7279f990bd222259fa9d362c1c18a60b38075..9455ff4477250b78e279040124dcc7215e2e351b 100644 (file)
--- a/src/black/cache.py
+++ b/src/black/cache.py
@@ -2,16 +2,14 @@
 
 import os
 import pickle
-from pathlib import Path
 import tempfile
+from pathlib import Path
 from typing import Dict, Iterable, Set, Tuple
 
 from platformdirs import user_cache_dir
 
-from black.mode import Mode
-
 from _black_version import version as __version__
-
+from black.mode import Mode
 
 # types
 Timestamp = float
@@ -20,7 +18,23 @@ CacheInfo = Tuple[Timestamp, FileSize]
 Cache = Dict[str, CacheInfo]
 
 
-CACHE_DIR = Path(user_cache_dir("black", version=__version__))
+def get_cache_dir() -> Path:
+    """Get the cache directory used by black.
+
+    Users can customize this directory on all systems using `BLACK_CACHE_DIR`
+    environment variable. By default, the cache directory is the user cache directory
+    under the black application.
+
+    This result is immediately set to a constant `black.cache.CACHE_DIR` as to avoid
+    repeated calls.
+    """
+    # NOTE: Function mostly exists as a clean way to test getting the cache directory.
+    default_cache_dir = user_cache_dir("black", version=__version__)
+    cache_dir = Path(os.environ.get("BLACK_CACHE_DIR", default_cache_dir))
+    return cache_dir
+
+
+CACHE_DIR = get_cache_dir()
 
 
 def read_cache(mode: Mode) -> Cache: