Replace try...finally with contextmanagers

Author: jlubken

src/pn532/example/__init__.py

@@ -2,6 +2,9 @@
 """Example."""
 
 from argparse import ArgumentParser
+from contextlib import contextmanager
+
+from RPi.GPIO import GPIO  # noqa: N814
 
 from pn532 import (
     PN532_SPI,
@@ -10,19 +13,31 @@
 )
 
 
-def spi():
-    """Return default spi device."""
-    return PN532_SPI(debug=False, reset=20, cs=4)
+@contextmanager
+def spi(debug=False, reset=20, cs=4):
+    """Yield a spi device."""
+    try:
+        yield PN532_SPI(debug=debug, reset=reset, cs=cs)
+    finally:
+        GPIO.cleanup()
 
 
-def i2c():
-    """Return default i2c device."""
-    return PN532_I2C(debug=False, reset=20, req=16)
+@contextmanager
+def i2c(debug=False, reset=20, req=16):
+    """Yield a i2c device."""
+    try:
+        yield PN532_I2C(debug=debug, reset=reset, req=req)
+    finally:
+        GPIO.cleanup()
 
 
-def uart():
-    """Return default uart device."""
-    return PN532_UART(debug=False, reset=20)
+@contextmanager
+def uart(debug=False, reset=20):
+    """Yield a uart device."""
+    try:
+        yield PN532_UART(debug=debug, reset=reset)
+    finally:
+        GPIO.cleanup()
 
 
 def mode(value):

src/pn532/example/gpio/read.py

@@ -5,16 +5,12 @@
 This example shows connecting to the PN532 and reading the GPIOs.
 """
 
-import RPi.GPIO as GPIO  # noqa: N814
-
 from pn532.example import parse_mode
 
 
 def run(mode):
     """Run."""
-    try:
-        pn532 = mode()
-
+    with mode() as pn532:
         ic, ver, rev, support = pn532.get_firmware_version()
         print("Found PN532 with firmware version: {0}.{1}".format(ver, rev))
 
@@ -29,8 +25,6 @@ def run(mode):
         print("i0:", pn532.read_gpio("I0"))
         print("i1:", pn532.read_gpio("I1"))
         print("P34:", pn532.read_gpio("P34"))
-    finally:
-        GPIO.cleanup()
 
 
 def main():

src/pn532/example/gpio/write.py

@@ -5,16 +5,12 @@
 This example shows connecting to the PN532 and writing the GPIOs.
 """
 
-import RPi.GPIO as GPIO  # noqa: N814
-
 from pn532.example import parse_mode
 
 
 def run(mode):
     """Run."""
-    try:
-        pn532 = mode()
-
+    with mode() as pn532:
         ic, ver, rev, support = pn532.get_firmware_version()
         print("Found PN532 with firmware version: {0}.{1}".format(ver, rev))
 
@@ -50,8 +46,6 @@ def run(mode):
         )
         print("2.  P71/P72 are always HIGH in SPI mode.")
         print("3.  DO NOT reset the P32 and P34 pins.")
-    finally:
-        GPIO.cleanup()
 
 
 def main():

src/pn532/example/mifare/dump.py

@@ -6,18 +6,14 @@
 type RFID tag
 """
 
-import RPi.GPIO as GPIO  # noqa: N814
-
 import pn532.pn532 as nfc
 
 from pn532.example import parse_mode
 
 
 def run(mode):
     """Run."""
-    try:
-        pn532 = mode()
-
+    with mode() as pn532:
         ic, ver, rev, support = pn532.get_firmware_version()
         print("Found PN532 with firmware version: {0}.{1}".format(ver, rev))
 
@@ -57,8 +53,6 @@ def run(mode):
             except nfc.PN532Error as e:
                 print(e.errmsg)
                 break
-    finally:
-        GPIO.cleanup()
 
 
 def main():

src/pn532/example/mifare/rw.py

@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 """
+Read/write mifare.
+
 This example shows connecting to the PN532 and writing an M1
 type RFID tag
 
@@ -13,17 +15,13 @@
 2.  Block 0 is unwritable.
 """
 
-import RPi.GPIO as GPIO  # noqa: N814
-
 import pn532.pn532 as nfc
 from pn532.example import parse_mode
 
 
 def run(mode):
     """Run."""
-    try:
-        pn532 = mode()
-
+    with mode() as pn532:
         ic, ver, rev, support = pn532.get_firmware_version()
         print("Found PN532 with firmware version: {0}.{1}".format(ver, rev))
 
@@ -86,8 +84,6 @@ def run(mode):
                 print("write block %d successfully" % block_number)
         except nfc.PN532Error as e:
             print(e.errmsg)
-    finally:
-        GPIO.cleanup()
 
 
 def main():

src/pn532/example/ntag2/dump.py

@@ -6,21 +6,15 @@
 type RFID tag
 """
 
-import RPi.GPIO as GPIO  # noqa: N814
-
 import pn532.pn532 as nfc
 from pn532.example import parse_mode
 
 
 def run(mode):
     """Run."""
-    try:
-        pn532 = mode()
-
+    with mode() as pn532:
         ic, ver, rev, support = pn532.get_firmware_version()
-        print(
-            "     Found PN532 with firmware version: {0}.{1}".format(ver, rev)
-        )
+        print(f"Found PN532 with firmware version: {ver}.{rev}")
 
         # Configure PN532 to communicate with NTAG215 cards
         pn532.SAM_configuration()
@@ -48,8 +42,6 @@ def run(mode):
             except nfc.PN532Error as e:
                 print(e.errmsg)
                 break
-    finally:
-        GPIO.cleanup()
 
 
 def main():

src/pn532/example/ntag2/rw.py

@@ -6,20 +6,16 @@
 type RFID tag
 """
 
-import RPi.GPIO as GPIO  # noqa: N814
-
 import pn532.pn532 as nfc
 
 from pn532.example import parse_mode
 
 
 def run(mode):
     """Run."""
-    try:
-        pn532 = mode()
-
+    with mode() as pn532:
         ic, ver, rev, support = pn532.get_firmware_version()
-        print("Found PN532 with firmware version: {0}.{1}".format(ver, rev))
+        print("Found PN532 with firmware version: {ver}.{rev}")
 
         # Configure PN532 to communicate with NTAG215 cards
         pn532.SAM_configuration()
@@ -44,8 +40,6 @@ def run(mode):
                 print("write block %d successfully" % block_number)
         except nfc.PN532Error as e:
             print(e.errmsg)
-    finally:
-        GPIO.cleanup()
 
 
 def main():

src/pn532/example/uid.py

@@ -8,16 +8,12 @@
 After initialization, try waving various 13.56MHz RFID cards over it!
 """
 
-import RPi.GPIO as GPIO  # noqa: N814
-
 from pn532.example import parse_mode
 
 
 def run(mode):
     """Run."""
-    try:
-        pn532 = mode()
-
+    with mode() as pn532:
         ic, ver, rev, support = pn532.get_firmware_version()
         print("Found PN532 with firmware version: {0}.{1}".format(ver, rev))
 
@@ -33,10 +29,6 @@ def run(mode):
             if uid is None:
                 continue
             print("Found card with UID:", [hex(i) for i in uid])
-    except Exception as e:
-        print(e)
-    finally:
-        GPIO.cleanup()
 
 
 def main():