Use __enter__ and __exit__ instead of __init__ and __del__

Execution of __del__ is not guaranteed due to the garbage collector.

Author: cyndis

linux/drm.py

@@ -44,15 +44,15 @@ def __init__(self):
         self.drmGetVersion.restype = drmVersionPtr
 
 class DRM:
-    def __init__(self, device):
+    def __enter__(self, device):
         self.libdrm = libdrm()
 
         if type(device) == str:
             self.fd = os.open(device, os.O_RDWR)
         elif type(device) == int:
             self.fd = device
 
-    def __del__(self):
+    def __exit__(self):
         os.close(self.fd)
 
     def GetVersion(self):
@@ -61,15 +61,7 @@ def GetVersion(self):
         self.libdrm.drmFreeVersion(version)
         return result
 
-def open(device):
-    if type(device) == str:
-        fd = os.open(device, os.O_RDWR)
-    elif type(device) == int:
-        fd = device
-
-    return DRM(fd)
-
 if __name__ == '__main__':
-    drm = open(sys.argv[1])
-    version = drm.GetVersion()
-    print(version)
+    with DRM(sys.argv[1]) as drm:
+        version = drm.GetVersion()
+        print(version)

linux/system.py

@@ -184,7 +184,7 @@ class Watchdog():
     WDIOS_DISABLECARD = 0x0001
     WDIOS_ENABLECARD = 0x0002
 
-    def __init__(self, path):
+    def __enter__(self, path):
         self.fd = os.open(path, os.O_RDWR)
 
     def disable(self):
@@ -202,7 +202,7 @@ def set_timeout(self, timeout):
 
         libc.ioctl(self.fd, Watchdog.WDIOC_SETTIMEOUT, timeout)
 
-    def __del__(self):
+    def __exit__(self):
         options = ctypes.pointer(ctypes.c_uint(Watchdog.WDIOS_DISABLECARD))
         libc.ioctl(self.fd, Watchdog.WDIOC_SETOPTIONS, options)
         os.close(self.fd)

linux/watchdog.py

@@ -11,7 +11,7 @@ class Watchdog():
     WDIOS_DISABLECARD = 0x0001
     WDIOS_ENABLECARD = 0x0002
 
-    def __init__(self, path):
+    def __enter__(self, path):
         self.fd = os.open(path, os.O_RDWR)
 
     def disable(self):
@@ -29,7 +29,7 @@ def set_timeout(self, timeout):
 
         libc.ioctl(self.fd, Watchdog.WDIOC_SETTIMEOUT, timeout)
 
-    def __del__(self):
+    def __exit__(self):
         options = ctypes.pointer(ctypes.c_uint(Watchdog.WDIOS_DISABLECARD))
         libc.ioctl(self.fd, Watchdog.WDIOC_SETOPTIONS, options)
         os.close(self.fd)

tests/drm.py

@@ -27,14 +27,14 @@ def test_list_devices(self):
             print('  %s (%u, %u)' % (device.device_node, os.major(devno),
                                      os.minor(devno)))
 
-            dev = linux.drm.open(device.device_node)
-            version = dev.GetVersion()
-            print('    Driver:', version.name)
-            print('      Description:', version.description)
-            print('      Version: %u.%u.%u (%s)' % (version.major,
-                                                    version.minor,
-                                                    version.patch,
-                                                    version.date))
+            with linux.drm.DRM(device.device_node) as dev:
+                version = dev.GetVersion()
+                print('    Driver:', version.name)
+                print('      Description:', version.description)
+                print('      Version: %u.%u.%u (%s)' % (version.major,
+                                                        version.minor,
+                                                        version.patch,
+                                                        version.date))
 
 submit_vic_path = '/root/drm/tests/tegra/submit_vic'
 def submit_vic_exists():

tests/system.py

@@ -45,6 +45,6 @@ class watchdog(unittest.TestCase):
     def test(self):
         print('Testing watchdog')
 
-        wdt = system.Watchdog('/dev/watchdog')
-        wdt.set_timeout(30)
-        wdt.enable()
+        with system.Watchdog('/dev/watchdog') as wdt:
+            wdt.set_timeout(30)
+            wdt.enable()