Original Translation
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The idea of list comprehensions originally comes from the functional programming language Haskell (http://www.haskell.org). Greg Ewing argued most effectively for adding them to Python and wrote the initial list comprehension patch, which was then discussed for a seemingly endless time on the python-dev mailing list and kept up-to-date by Skip Montanaro.
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Augmented Assignment
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Augmented assignment operators, another long-requested feature, have been added to Python 2.0. Augmented assignment operators include ``+=``, ``-=``, ``*=``, and so forth. For example, the statement ``a += 2`` increments the value of the variable ``a`` by 2, equivalent to the slightly lengthier ``a = a + 2``.
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The full list of supported assignment operators is ``+=``, ``-=``, ``*=``, ``/=``, ``%=``, ``**=``, ``&=``, ``|=``, ``^=``, ``>>=``, and ``<<=``. Python classes can override the augmented assignment operators by defining methods named :meth:`__iadd__`, :meth:`__isub__`, etc. For example, the following :class:`Number` class stores a number and supports using += to create a new instance with an incremented value.
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class Number: def __init__(self, value): self.value = value def __iadd__(self, increment): return Number( self.value + increment) n = Number(5) n += 3 print n.value
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The :meth:`__iadd__` special method is called with the value of the increment, and should return a new instance with an appropriately modified value; this return value is bound as the new value of the variable on the left-hand side.
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Augmented assignment operators were first introduced in the C programming language, and most C-derived languages, such as :program:`awk`, C++, Java, Perl, and PHP also support them. The augmented assignment patch was implemented by Thomas Wouters.
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String Methods
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Until now string-manipulation functionality was in the :mod:`string` module, which was usually a front-end for the :mod:`strop` module written in C. The addition of Unicode posed a difficulty for the :mod:`strop` module, because the functions would all need to be rewritten in order to accept either 8-bit or Unicode strings. For functions such as :func:`string.replace`, which takes 3 string arguments, that means eight possible permutations, and correspondingly complicated code.
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Instead, Python 2.0 pushes the problem onto the string type, making string manipulation functionality available through methods on both 8-bit strings and Unicode strings. ::