Merge pull request fluentpython#3 from eumiro/py36plus

Modernize code to Python 3.6+ and some cleanup

Author: ramalho

01-data-model/vector2d.py

@@ -26,7 +26,6 @@
     >>> abs(v * 3)
     15.0
 
-    
 """
 
 
@@ -39,7 +38,7 @@ def __init__(self, x=0, y=0):
         self.y = y
 
     def __repr__(self):
-        return 'Vector(%r, %r)' % (self.x, self.y)
+        return f'Vector({self.x!r}, {self.y!r})'
 
     def __abs__(self):
         return hypot(self.x, self.y)

02-array-seq/bisect_demo.py

@@ -11,11 +11,11 @@
     23 @ 11      |  |  |  |  |  |  |  |  |  |  |23
     22 @  9      |  |  |  |  |  |  |  |  |22
     10 @  5      |  |  |  |  |10
-     8 @  5      |  |  |  |  |8 
-     5 @  3      |  |  |5 
-     2 @  1      |2 
-     1 @  1      |1 
-     0 @  0    0 
+     8 @  5      |  |  |  |  |8
+     5 @  3      |  |  |5
+     2 @  1      |2
+     1 @  1      |1
+     0 @  0    0
 
 
 Demonstration of ``bisect.bisect_left``::
@@ -27,11 +27,11 @@
     23 @  9      |  |  |  |  |  |  |  |  |23
     22 @  9      |  |  |  |  |  |  |  |  |22
     10 @  5      |  |  |  |  |10
-     8 @  4      |  |  |  |8 
-     5 @  2      |  |5 
-     2 @  1      |2 
-     1 @  0    1 
-     0 @  0    0 
+     8 @  4      |  |  |  |8
+     5 @  2      |  |5
+     2 @  1      |2
+     1 @  0    1
+     0 @  0    0
 
 
 """
@@ -59,7 +59,7 @@ def demo(bisect_fn):
         bisect_fn = bisect.bisect
 
     print('DEMO:', bisect_fn.__name__)  # <5>
-    print('haystack ->', ' '.join('%2d' % n for n in HAYSTACK))
+    print('haystack ->', ' '.join(f'{n:2}' for n in HAYSTACK))
     demo(bisect_fn)
 
 # END BISECT_DEMO

02-array-seq/bisect_insort.py

@@ -7,6 +7,6 @@
 
 my_list = []
 for i in range(SIZE):
-    new_item = random.randrange(SIZE*2)
+    new_item = random.randrange(SIZE * 2)
     bisect.insort(my_list, new_item)
-    print('%2d ->' % new_item, my_list)
+    print(f'{new_item:2} ->', my_list)

02-array-seq/listcomp_speed.py

@@ -10,7 +10,7 @@ def non_ascii(c):
 
 def clock(label, cmd):
     res = timeit.repeat(cmd, setup=SETUP, number=TIMES)
-    print(label, *('{:.3f}'.format(x) for x in res))
+    print(label, *(f'{x:.3f}' for x in res))
 
 clock('listcomp        :', '[ord(s) for s in symbols if ord(s) > 127]')
 clock('listcomp + func :', '[ord(s) for s in symbols if non_ascii(ord(s))]')

02-array-seq/metro_lat_long.py

@@ -4,7 +4,7 @@
 Demonstration of nested tuple unpacking::
 
     >>> main()
-                    |   lat.    |   long.  
+                    |   lat.    |   long.
     Mexico City     |   19.4333 |  -99.1333
     New York-Newark |   40.8086 |  -74.0204
     Sao Paulo       |  -23.5478 |  -46.6358
@@ -20,11 +20,10 @@
 ]
 
 def main():
-    print('{:15} | {:^9} | {:^9}'.format('', 'lat.', 'long.'))
-    fmt = '{:15} | {:9.4f} | {:9.4f}'
+    print(f'{"":15} | {"lat.":^9} | {"long.":^9}')
     for name, cc, pop, (latitude, longitude) in metro_areas:  # <2>
         if longitude <= 0:  # <3>
-            print(fmt.format(name, latitude, longitude))
+            print(f'{name:15} | {latitude:9.4f} | {longitude:9.4f}')
 
 if __name__ == '__main__':
     main()

03-dict-set/index_default.py

@@ -16,7 +16,7 @@
     for line_no, line in enumerate(fp, 1):
         for match in WORD_RE.finditer(line):
             word = match.group()
-            column_no = match.start()+1
+            column_no = match.start() + 1
             location = (line_no, column_no)
             index[word].append(location)  # <2>
 

03-dict-set/support/container_perftest.py

@@ -41,15 +41,15 @@ def test(container_type, verbose):
                              size=size, verbose=verbose)
         test = TEST.format(verbose=verbose)
         tt = timeit.repeat(stmt=test, setup=setup, repeat=5, number=1)
-        print('|{:{}d}|{:f}'.format(size, MAX_EXPONENT + 1, min(tt)))
+        print(f'|{size:{MAX_EXPONENT + 1}d}|{min(tt):f}')
 
-if __name__=='__main__':
+if __name__ == '__main__':
     if '-v' in sys.argv:
         sys.argv.remove('-v')
         verbose = True
     else:
         verbose = False
     if len(sys.argv) != 2:
-        print('Usage: %s <container_type>' % sys.argv[0])
+        print(f'Usage: {sys.argv[0]} <container_type>')
     else:
         test(sys.argv[1], verbose)

03-dict-set/support/container_perftest_datagen.py

@@ -2,8 +2,8 @@
 Generate data for container performance test
 """
 
-import random
 import array
+import random
 
 MAX_EXPONENT = 7
 HAYSTACK_LEN = 10 ** MAX_EXPONENT
@@ -12,26 +12,26 @@
 
 needles = array.array('d')
 
-sample = {1/random.random() for i in range(SAMPLE_LEN)}
-print('initial sample: %d elements' % len(sample))
+sample = {1 / random.random() for i in range(SAMPLE_LEN)}
+print(f'initial sample: {len(sample)} elements')
 
 # complete sample, in case duplicate random numbers were discarded
 while len(sample) < SAMPLE_LEN:
-    sample.add(1/random.random())
+    sample.add(1 / random.random())
 
-print('complete sample: %d elements' % len(sample))
+print(f'complete sample: {len(sample)} elements')
 
 sample = array.array('d', sample)
 random.shuffle(sample)
 
 not_selected = sample[:NEEDLES_LEN // 2]
-print('not selected: %d samples' % len(not_selected))
+print(f'not selected: {len(not_selected)} samples')
 print('  writing not_selected.arr')
 with open('not_selected.arr', 'wb') as fp:
     not_selected.tofile(fp)
 
 selected = sample[NEEDLES_LEN // 2:]
-print('selected: %d samples' % len(selected))
+print(f'selected: {len(selected)} samples')
 print('  writing selected.arr')
 with open('selected.arr', 'wb') as fp:
     selected.tofile(fp)

03-dict-set/support/hashdiff.py

@@ -1,17 +1,17 @@
 import sys
 
 MAX_BITS = len(format(sys.maxsize, 'b'))
-print('%s-bit Python build' % (MAX_BITS + 1))
+print(f'{MAX_BITS + 1}-bit Python build')
 
 def hash_diff(o1, o2):
-    h1 = '{:>0{}b}'.format(hash(o1), MAX_BITS)
-    h2 = '{:>0{}b}'.format(hash(o2), MAX_BITS)
+    h1 = f'{hash(o1):>0{MAX_BITS}b}'
+    h2 = f'{hash(o2):>0{MAX_BITS}b}'
     diff = ''.join('!' if b1 != b2 else ' ' for b1, b2 in zip(h1, h2))
-    count = '!= {}'.format(diff.count('!'))
+    count = f'!= {diff.count("!")}'
     width = max(len(repr(o1)), len(repr(o2)), 8)
     sep = '-' * (width * 2 + MAX_BITS)
-    return '{!r:{width}} {}\n{:{width}} {} {}\n{!r:{width}} {}\n{}'.format(
-    		o1, h1, ' ' * width, diff, count, o2, h2, sep, width=width)
+    return (f'{o1!r:{width}} {h1}\n{" ":{width}} {diff} {count}\n'
+            f'{o2!r:{width}} {h2}\n{sep}')
 
 if __name__ == '__main__':
     print(hash_diff(1, 1.0))

03-dict-set/transformdict.py

@@ -17,7 +17,7 @@
 
 
 class TransformDict(MutableMapping):
-    '''Dictionary that calls a transformation function when looking
+    """Dictionary that calls a transformation function when looking
     up keys, but preserves the original keys.
 
     >>> d = TransformDict(str.lower)
@@ -26,18 +26,18 @@ class TransformDict(MutableMapping):
     True
     >>> set(d.keys())
     {'Foo'}
-    '''
+    """
 
     __slots__ = ('_transform', '_original', '_data')
 
     def __init__(self, transform, init_dict=None, **kwargs):
-        '''Create a new TransformDict with the given *transform* function.
+        """Create a new TransformDict with the given *transform* function.
         *init_dict* and *kwargs* are optional initializers, as in the
         dict constructor.
-        '''
+        """
         if not callable(transform):
-            msg = 'expected a callable, got %r'
-            raise TypeError(msg % transform.__class__)
+            raise TypeError(
+                f'expected a callable, got {transform.__class__!r}')
         self._transform = transform
         # transformed => original
         self._original = {}
@@ -48,15 +48,15 @@ def __init__(self, transform, init_dict=None, **kwargs):
             self.update(kwargs)
 
     def getitem(self, key):
-        'D.getitem(key) -> (stored key, value)'
+        """D.getitem(key) -> (stored key, value)"""
         transformed = self._transform(key)
         original = self._original[transformed]
         value = self._data[transformed]
         return original, value
 
     @property
     def transform_func(self):
-        "This TransformDict's transformation function"
+        """This TransformDict's transformation function"""
         return self._transform
 
     # Minimum set of methods required for MutableMapping
@@ -83,22 +83,22 @@ def __delitem__(self, key):
     # Methods overridden to mitigate the performance overhead.
 
     def clear(self):
-        'D.clear() -> None.  Remove all items from D.'
+        """D.clear() -> None.  Remove all items from D."""
         self._data.clear()
         self._original.clear()
 
     def __contains__(self, key):
         return self._transform(key) in self._data
 
     def get(self, key, default=None):
-        'D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None.'
+        """D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None."""
         return self._data.get(self._transform(key), default)
 
     def pop(self, key, default=_sentinel):
-        '''D.pop(k[,d]) -> v, remove key and return corresponding value.
+        """D.pop(k[,d]) -> v, remove key and return corresponding value.
            If key is not found, d is returned if given, otherwise
            KeyError is raised.
-        '''
+        """
         transformed = self._transform(key)
         if default is _sentinel:
             del self._original[transformed]
@@ -108,16 +108,16 @@ def pop(self, key, default=_sentinel):
             return self._data.pop(transformed, default)
 
     def popitem(self):
-        '''D.popitem() -> (k, v), remove and return some (key, value) pair
+        """D.popitem() -> (k, v), remove and return some (key, value) pair
            as a 2-tuple; but raise KeyError if D is empty.
-        '''
+        """
         transformed, value = self._data.popitem()
         return self._original.pop(transformed), value
 
     # Other methods
 
     def copy(self):
-        'D.copy() -> a shallow copy of D'
+        """D.copy() -> a shallow copy of D"""
         other = self.__class__(self._transform)
         other._original = self._original.copy()
         other._data = self._data.copy()
@@ -137,5 +137,4 @@ def __repr__(self):
         except TypeError:
             # Some keys are unhashable, fall back on .items()
             equiv = list(self.items())
-        return '%s(%r, %s)' % (self.__class__.__name__,
-                               self._transform, repr(equiv))
+        return f'{self.__class__.__name__}({self._transform!r}, {equiv!r})'