Mercurial > cpython-lru_cache-weakref
annotate Demo/classes/Range.py @ 5817:48b94de85bf3 legacy-trunk
Extensive changes by AMK.
| author | Guido van Rossum <guido@python.org> |
|---|---|
| date | Thu, 17 Jul 1997 16:29:42 +0000 |
| parents | b70f08907546 |
| children | 558689b6d7f0 |
| rev | line source |
|---|---|
| 945 | 1 # Example of a generator: re-implement the built-in range function |
| 2 # without actually constructing the list of values. (It turns out | |
| 3 # that the built-in function is about 20 times faster -- that's why | |
| 4 # it's built-in. :-) | |
| 5 | |
| 6 | |
| 7 # Wrapper function to emulate the complicated range() arguments | |
| 8 | |
| 9 def range(*a): | |
| 10 if len(a) == 1: | |
| 11 start, stop, step = 0, a[0], 1 | |
| 12 elif len(a) == 2: | |
| 13 start, stop = a | |
| 14 step = 1 | |
| 15 elif len(a) == 3: | |
| 16 start, stop, step = a | |
| 17 else: | |
| 18 raise TypeError, 'range() needs 1-3 arguments' | |
|
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Guido van Rossum <guido@python.org>
parents:
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19 return Range(start, stop, step) |
| 945 | 20 |
| 21 | |
| 22 # Class implementing a range object. | |
| 23 # To the user the instances feel like immutable sequences | |
| 24 # (and you can't concatenate or slice them) | |
| 25 | |
| 26 class Range: | |
| 27 | |
| 28 # initialization -- should be called only by range() above | |
|
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29 def __init__(self, start, stop, step): |
| 945 | 30 if step == 0: |
| 31 raise ValueError, 'range() called with zero step' | |
| 32 self.start = start | |
| 33 self.stop = stop | |
| 34 self.step = step | |
| 35 self.len = max(0, int((self.stop - self.start) / self.step)) | |
| 36 | |
| 37 # implement `x` and is also used by print x | |
| 38 def __repr__(self): | |
| 39 return 'range' + `self.start, self.stop, self.step` | |
| 40 | |
| 41 # implement len(x) | |
| 42 def __len__(self): | |
| 43 return self.len | |
| 44 | |
| 45 # implement x[i] | |
| 46 def __getitem__(self, i): | |
| 47 if 0 <= i < self.len: | |
| 48 return self.start + self.step * i | |
| 49 else: | |
| 50 raise IndexError, 'range[i] index out of range' | |
| 51 | |
| 52 | |
| 53 # Small test program | |
| 54 | |
| 55 def test(): | |
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56 import time, __builtin__ |
| 945 | 57 print range(10), range(-10, 10), range(0, 10, 2) |
| 58 for i in range(100, -100, -10): print i, | |
| 59 print | |
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60 t1 = time.time() |
| 945 | 61 for i in range(1000): |
| 62 pass | |
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Use time.time() instead of time.millitimer()
Guido van Rossum <guido@python.org>
parents:
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63 t2 = time.time() |
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builtin -> __builtin__
Guido van Rossum <guido@python.org>
parents:
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changeset
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64 for i in __builtin__.range(1000): |
| 945 | 65 pass |
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Use time.time() instead of time.millitimer()
Guido van Rossum <guido@python.org>
parents:
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diff
changeset
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66 t3 = time.time() |
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b70f08907546
Use time.time() instead of time.millitimer()
Guido van Rossum <guido@python.org>
parents:
1532
diff
changeset
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67 print t2-t1, 'sec (class)' |
|
b70f08907546
Use time.time() instead of time.millitimer()
Guido van Rossum <guido@python.org>
parents:
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68 print t3-t2, 'sec (built-in)' |
| 945 | 69 |
| 70 | |
| 71 test() |