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Diffstat (limited to 'Doc/faq/design.rst')
| -rw-r--r-- | Doc/faq/design.rst | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/Doc/faq/design.rst b/Doc/faq/design.rst index c42cccb..1b6cd7e 100644 --- a/Doc/faq/design.rst +++ b/Doc/faq/design.rst @@ -158,7 +158,7 @@ where in Python you're forced to write this:: line = f.readline() if not line: break - ... # do something with line + ... # do something with line The reason for not allowing assignment in Python expressions is a common, hard-to-find bug in those other languages, caused by this construct: @@ -190,7 +190,7 @@ generally less robust than the "while True" solution:: line = f.readline() while line: - ... # do something with line... + ... # do something with line... line = f.readline() The problem with this is that if you change your mind about exactly how you get @@ -203,7 +203,7 @@ objects using the ``for`` statement. For example, :term:`file objects <file object>` support the iterator protocol, so you can write simply:: for line in f: - ... # do something with line... + ... # do something with line... @@ -577,8 +577,10 @@ other structure). :: class ListWrapper: def __init__(self, the_list): self.the_list = the_list + def __eq__(self, other): return self.the_list == other.the_list + def __hash__(self): l = self.the_list result = 98767 - len(l)*555 @@ -619,7 +621,7 @@ it and returns it. For example, here's how to iterate over the keys of a dictionary in sorted order:: for key in sorted(mydict): - ... # do whatever with mydict[key]... + ... # do whatever with mydict[key]... How do you specify and enforce an interface spec in Python? @@ -675,11 +677,11 @@ languages. For example:: class label(Exception): pass # declare a label try: - ... - if condition: raise label() # goto label - ... + ... + if condition: raise label() # goto label + ... except label: # where to goto - pass + pass ... This doesn't allow you to jump into the middle of a loop, but that's usually |