3c4bfd1dec
This commit adds the errno attribute to exceptions, so code can retrieve errno codes from an OSError using exc.errno. The implementation here simply lets `errno` (and the existing `value`) attributes work on any exception instance (they both alias args[0]). This is for efficiency and to keep code size down. The pros and cons of this are: Pros: - more compatible with CPython, less difference to document and learn - OSError().errno will correctly return None, whereas the current way of doing it via OSError().args[0] will raise an IndexError - it reduces code size on most bare-metal ports (because they already have the errno qstr) - for Python code that uses exc.errno the generated bytecode is 2 bytes smaller and more efficient to execute (compared with exc.args[0]); so bytecode loaded to RAM saves 2 bytes RAM for each use of this attribute, and bytecode that is frozen saves 2 bytes flash/ROM for each use - it's easier/shorter to type, and saves 2 bytes of space in .py files that use it (for each use) Cons: - increases code size by 4-8 bytes on minimal ports that don't already have the `errno` qstr - all exceptions now have .errno and .value attributes (a cpydiff test is added to address this) See also #2407. Signed-off-by: Damien George <damien@micropython.org>
43 lines
634 B
Python
43 lines
634 B
Python
# test subclassing a native exception
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class MyExc(Exception):
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pass
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e = MyExc(100, "Some error")
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print(e)
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print(repr(e))
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print(e.args)
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try:
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raise MyExc("Some error", 1)
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except MyExc as e:
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print("Caught exception:", repr(e))
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try:
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raise MyExc("Some error2", 2)
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except Exception as e:
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print("Caught exception:", repr(e))
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try:
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raise MyExc("Some error2")
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except:
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print("Caught user exception")
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class MyStopIteration(StopIteration):
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pass
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print(MyStopIteration().value)
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print(MyStopIteration(1).value)
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class MyOSError(OSError):
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pass
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print(MyOSError().errno)
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print(MyOSError(1, "msg").errno)
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