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programming:python [2017/08/02 14:07] niziak |
programming:python [2020/07/03 09:51] (current) niziak ↷ Page moved from python to programming:python |
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| + | ====== Python ====== | ||
| + | |||
| + | ====== OOP ====== | ||
| + | |||
| + | ===== Call parent constuctor ====== | ||
| + | |||
| + | <code python>super().__init__()</code> | ||
| + | |||
| + | ====== String formatting ====== | ||
| + | |||
| + | * using the % operator (old) | ||
| + | <code python> | ||
| + | logger.debug('Got argument %s.' % arg) | ||
| + | </code> | ||
| + | |||
| + | * str.format (new: string formatters) | ||
| + | <code python> | ||
| + | print("Sammy has {} balloons.".format(5)) | ||
| + | print("Sammy has {} and {} balloons.".format(5, 7)) | ||
| + | print("Sammy has {0} and {1} balloons.".format(5, 7)) | ||
| + | print("Sammy has {1} and {0} balloons.".format(5, 7)) | ||
| + | </code> | ||
| + | |||
| + | * interpolated strings | ||
| + | <code python> | ||
| + | print("{firstname} {lastname}".format(firstname="Horst", lastname="Gutmann")) | ||
| + | </code> | ||
| + | |||
| + | * new f-strings in Python 3.6 | ||
| + | <code python> | ||
| + | name = 'Fred' | ||
| + | age = 42 | ||
| + | print(f'He said his name is {name} and he is {age} years old.') | ||
| + | </code> | ||
| + | |||
| + | ===== logger ===== | ||
| + | |||
| + | Logger is optimized to defer avaluation of arguments until it is needed, so for best performance use ''%'' formating. | ||
| + | Instead of this: | ||
| + | <code python>logger.error('oops caused by %s' % exc)</code> | ||
| + | do that: | ||
| + | <code python>logger.error('oops caused by %s', exc)</code> | ||
| + | |||
| + | |||
| ====== Exceptions ====== | ====== Exceptions ====== | ||
| * [[https://docs.python.org/3/library/exceptions.html#exception-hierarchy|exception-hierarchy]] | * [[https://docs.python.org/3/library/exceptions.html#exception-hierarchy|exception-hierarchy]] | ||
| Line 6: | Line 50: | ||
| <code python> | <code python> | ||
| - | except: | + | try: |
| + | do_something() | ||
| + | except Exception: | ||
| pass | pass | ||
| </code> | </code> | ||