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annotate planemo/lib/python3.7/site-packages/future/builtins/newnext.py @ 1:56ad4e20f292 draft

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"planemo upload commit 6eee67778febed82ddd413c3ca40b3183a3898f1"
author guerler
date Fri, 31 Jul 2020 00:32:28 -0400
parents d30785e31577
children
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1 '''
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2 This module provides a newnext() function in Python 2 that mimics the
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3 behaviour of ``next()`` in Python 3, falling back to Python 2's behaviour for
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4 compatibility if this fails.
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5
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6 ``newnext(iterator)`` calls the iterator's ``__next__()`` method if it exists. If this
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7 doesn't exist, it falls back to calling a ``next()`` method.
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8
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9 For example:
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10
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11 >>> class Odds(object):
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12 ... def __init__(self, start=1):
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13 ... self.value = start - 2
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14 ... def __next__(self): # note the Py3 interface
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15 ... self.value += 2
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16 ... return self.value
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17 ... def __iter__(self):
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18 ... return self
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19 ...
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20 >>> iterator = Odds()
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21 >>> next(iterator)
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22 1
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23 >>> next(iterator)
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24 3
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25
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26 If you are defining your own custom iterator class as above, it is preferable
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27 to explicitly decorate the class with the @implements_iterator decorator from
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28 ``future.utils`` as follows:
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29
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30 >>> @implements_iterator
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31 ... class Odds(object):
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32 ... # etc
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33 ... pass
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34
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35 This next() function is primarily for consuming iterators defined in Python 3
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36 code elsewhere that we would like to run on Python 2 or 3.
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37 '''
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38
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39 _builtin_next = next
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40
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41 _SENTINEL = object()
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42
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43 def newnext(iterator, default=_SENTINEL):
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44 """
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45 next(iterator[, default])
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46
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47 Return the next item from the iterator. If default is given and the iterator
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48 is exhausted, it is returned instead of raising StopIteration.
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49 """
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50
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51 # args = []
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52 # if default is not _SENTINEL:
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53 # args.append(default)
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54 try:
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55 try:
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56 return iterator.__next__()
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57 except AttributeError:
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58 try:
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59 return iterator.next()
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60 except AttributeError:
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61 raise TypeError("'{0}' object is not an iterator".format(
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62 iterator.__class__.__name__))
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63 except StopIteration as e:
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64 if default is _SENTINEL:
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65 raise e
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66 else:
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67 return default
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68
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69
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70 __all__ = ['newnext']