2018-04-24 18:31 GMT+03:00 Chris Angelico
Recommended use-cases =====================
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# Capturing regular expression match objects # See, for instance, Lib/pydoc.py, which uses a multiline spelling # of this effect if match := re.search(pat, text): print("Found:", match.group(0))
Not sure, but if additional motivating examples are required, there is a common pattern for dynamic attribute lookup (snippet from `copy.py`): reductor = dispatch_table.get(cls) if reductor: rv = reductor(x) else: reductor = getattr(x, "__reduce_ex__", None) if reductor: rv = reductor(4) else: reductor = getattr(x, "__reduce__", None) if reductor: rv = reductor() else: raise Error("un(shallow)copyable object of type %s" % cls) which can with the current `binding expression` syntax simplified to: if reductor := dispatch_table.get(cls): rv = reductor(x) elif reductor := getattr(x, "__reduce_ex__", None): rv = reductor(4) elif reductor := getattr(x, "__reduce__", None): rv = reductor() else: raise Error("un(shallow)copyable object of type %s" % cls) which becomes much clearer, at least in my opinion. With kind regards, -gdg