ch08, 09, 10: example files

09-closure-deco/htmlizer.py

@@ -0,0 +1,76 @@
+r"""
+htmlize(): generic function example
+
+# tag::HTMLIZE_DEMO[]
+
+>>> htmlize({1, 2, 3})  # <1>
+'<pre>{1, 2, 3}</pre>'
+>>> htmlize(abs)
+'<pre>&lt;built-in function abs&gt;</pre>'
+>>> htmlize('Heimlich & Co.\n- a game')  # <2>
+'<p>Heimlich &amp; Co.<br>\n- a game</p>'
+>>> htmlize(42)  # <3>
+'<pre>42 (0x2a)</pre>'
+>>> print(htmlize(['alpha', 66, {3, 2, 1}]))  # <4>
+<ul>
+<li><p>alpha</p></li>
+<li><pre>66 (0x42)</pre></li>
+<li><pre>{1, 2, 3}</pre></li>
+</ul>
+>>> htmlize(True)  # <5>
+'<pre>True</pre>'
+>>> htmlize(fractions.Fraction(2, 3))  # <6>
+'<pre>2/3</pre>'
+>>> htmlize(2/3)   # <7>
+'<pre>0.6666666666666666 (2/3)</pre>'
+>>> htmlize(decimal.Decimal('0.02380952'))
+'<pre>0.02380952 (1/42)</pre>'
+
+# end::HTMLIZE_DEMO[]
+"""
+
+# tag::HTMLIZE[]
+
+from functools import singledispatch
+from collections import abc
+import fractions
+import decimal
+import html
+import numbers
+
+@singledispatch  # <1>
+def htmlize(obj: object) -> str:
+    content = html.escape(repr(obj))
+    return f'<pre>{content}</pre>'
+
+@htmlize.register  # <2>
+def _(text: str) -> str:  # <3>
+    content = html.escape(text).replace('\n', '<br>\n')
+    return f'<p>{content}</p>'
+
+@htmlize.register  # <4>
+def _(seq: abc.Sequence) -> str:
+    inner = '</li>\n<li>'.join(htmlize(item) for item in seq)
+    return '<ul>\n<li>' + inner + '</li>\n</ul>'
+
+@htmlize.register  # <5>
+def _(n: numbers.Integral) -> str:
+    return f'<pre>{n} (0x{n:x})</pre>'
+
+@htmlize.register  # <6>
+def _(n: bool) -> str:
+    return f'<pre>{n}</pre>'
+
+@htmlize.register(fractions.Fraction)  # <7>
+def _(x) -> str:
+    frac = fractions.Fraction(x)
+    return f'<pre>{frac.numerator}/{frac.denominator}</pre>'
+
+@htmlize.register(decimal.Decimal)  # <8>
+@htmlize.register(float)
+def _(x) -> str:
+    frac = fractions.Fraction(x).limit_denominator()
+    return f'<pre>{x} ({frac.numerator}/{frac.denominator})</pre>'
+
+# end::HTMLIZE[]
+