ch07: example files

Author: ramalho

07-1class-func/README.rst

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+Sample code for Chapter 7 - "First-class functions"
+
+From the book "Fluent Python, Second Edition" by Luciano Ramalho (O'Reilly, 2020)
+http://shop.oreilly.com/product/0636920273196.do

07-1class-func/bingocall.py

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+"""
+# tag::BINGO_DEMO[]
+
+>>> bingo = BingoCage(range(3))
+>>> bingo.pick()
+1
+>>> bingo()
+0
+>>> callable(bingo)
+True
+
+# end::BINGO_DEMO[]
+
+"""
+
+# tag::BINGO[]
+
+import random
+
+class BingoCage:
+
+    def __init__(self, items):
+        self._items = list(items)  # <1>
+        random.shuffle(self._items)  # <2>
+
+    def pick(self):  # <3>
+        try:
+            return self._items.pop()
+        except IndexError:
+            raise LookupError('pick from empty BingoCage')  # <4>
+
+    def __call__(self):  # <5>
+        return self.pick()
+
+# end::BINGO[]

07-1class-func/clip.py

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+"""
+    >>> clip('banana ', 6)
+    'banana'
+    >>> clip('banana ', 7)
+    'banana'
+    >>> clip('banana ', 5)
+    'banana'
+    >>> clip('banana split', 6)
+    'banana'
+    >>> clip('banana split', 7)
+    'banana'
+    >>> clip('banana split', 10)
+    'banana'
+    >>> clip('banana split', 11)
+    'banana'
+    >>> clip('banana split', 12)
+    'banana split'
+"""
+
+# tag::CLIP[]
+def clip(text, max_len=80):
+    """Return text clipped at the last space before or after max_len
+    """
+    end = None
+    if len(text) > max_len:
+        space_before = text.rfind(' ', 0, max_len)
+        if space_before >= 0:
+            end = space_before
+        else:
+            space_after = text.rfind(' ', max_len)
+            if space_after >= 0:
+                end = space_after
+    if end is None:  # no spaces were found
+        return text.rstrip()
+    return text[:end].rstrip()
+# end::CLIP[]

07-1class-func/clip_introspection.rst

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+>>> from clip import clip
+>>> clip.__defaults__
+(80,)
+>>> clip.__code__  # doctest: +ELLIPSIS
+<code object clip at 0x...>
+>>> clip.__code__.co_varnames
+('text', 'max_len', 'end', 'space_before', 'space_after')
+>>> clip.__code__.co_argcount
+2

07-1class-func/clip_signature.rst

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+>>> from clip import clip
+>>> from inspect import signature
+>>> sig = signature(clip)
+>>> sig  # doctest: +ELLIPSIS
+<inspect.Signature object at 0x...>
+>>> str(sig)
+'(text, max_len=80)'
+>>> for name, param in sig.parameters.items():
+...     print(param.kind, ':', name, '=', param.default)
+...
+POSITIONAL_OR_KEYWORD : text = <class 'inspect._empty'>
+POSITIONAL_OR_KEYWORD : max_len = 80

07-1class-func/tagger.py

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+
+
+"""
+# tag::TAG_DEMO[]
+>>> tag('br')  # <1>
+'<br />'
+>>> tag('p', 'hello')  # <2>
+'<p>hello</p>'
+>>> print(tag('p', 'hello', 'world'))
+<p>hello</p>
+<p>world</p>
+>>> tag('p', 'hello', id=33)  # <3>
+'<p id="33">hello</p>'
+>>> print(tag('p', 'hello', 'world', class_='sidebar'))  # <4>
+<p class="sidebar">hello</p>
+<p class="sidebar">world</p>
+>>> tag(content='testing', name="img")  # <5>
+'<img content="testing" />'
+>>> my_tag = {'name': 'img', 'title': 'Sunset Boulevard',
+...           'src': 'sunset.jpg', 'class': 'framed'}
+>>> tag(**my_tag)  # <6>
+'<img class="framed" src="sunset.jpg" title="Sunset Boulevard" />'
+
+# end::TAG_DEMO[]
+"""
+
+
+# tag::TAG_FUNC[]
+def tag(name, *content, class_=None, **attrs):
+    """Generate one or more HTML tags"""
+    if class_ is not None:
+        attrs['class'] = class_
+    if attrs:
+        attr_pairs = (f' {attr}="{value}"' for attr, value
+                      in sorted(attrs.items()))
+        attr_str = ''.join(attr_pairs)
+    else:
+        attr_str = ''
+    if content:
+        elements = (f'<{name}{attr_str}>{c}</{name}>'
+                    for c in content)
+        return '\n'.join(elements)
+    else:
+        return f'<{name}{attr_str} />'
+# end::TAG_FUNC[]