Appease linter: No global variables

diff --git a/pinch.py b/pinch.py
index c26070b17ee00eac25b191454f32f54b45e58b3c..9555d74567f7b27ea76cb700beb87a31ed1db0b8 100644 (file)
--- a/pinch.py
+++ b/pinch.py
@@ -302,18 +302,17 @@ def digest_file(filename: str) -> Digest16:
     return Digest16(hasher.hexdigest())
 
 
-_experimental_flag_needed = None
+@functools.lru_cache
+def _experimental_flag_needed(v: Verification) -> bool:
+    v.status('Checking Nix version')
+    process = subprocess.run(['nix', '--help'], stdout=subprocess.PIPE)
+    v.result(process.returncode == 0)
+    return b'--experimental-features' in process.stdout
 
 
 def _nix_command(v: Verification) -> List[str]:
-    global _experimental_flag_needed
-    if _experimental_flag_needed is None:
-        v.status('Checking Nix version')
-        process = subprocess.run(['nix', '--help'], stdout=subprocess.PIPE)
-        v.result(process.returncode == 0)
-        _experimental_flag_needed = b'--experimental-features' in process.stdout
     return ['nix', '--experimental-features',
-            'nix-command'] if _experimental_flag_needed else ['nix']
+            'nix-command'] if _experimental_flag_needed(v) else ['nix']
 
 
 def to_Digest16(v: Verification, digest32: Digest32) -> Digest16: