Index. Cache, 20 Callables, 185 call () method, 290 chain() function, 41 Classes attributes descriptors, 145 properties, 143

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1 Index A add_column() method, 284 add() method, 44 addtypeequalityfunc() method, 253 Affero General Public License (AGPL), 260 American Standard Code for Information Interchange (ASCII), and operator, 34 append() method, 44 attach_to_class() method, 277 Attributes, doc attribute, 335 B Backward compatibility policy making incompatible changes, 342 Python 3.0, 344 rules, Berkeley Software Distribution (BSD) license, 261 Bound methods, 149 Built-in id() function, 189 Byte string chr() and ord(), 214 standard strings, 213 struct module, 215 C Cache, 20 Callables, 185 call () method, 290 chain() function, 41 Classes attributes descriptors, 145 properties, 143 creation metaclasses, 137 namespace controlling, 141 plugin framework, 138 runtime, 135 docstrings, 337 inheritance contact class, 116 get and set functions, 116 introspection, 133 MRO (see Method resolution order (MRO)) multiple inheritance, 118 Person and Company classes, 117 Python class, 116 magic methods attributes, 155 automatic subclasses, 154 instantiation creation, 153 string representations, 158 methods assigning functions, 152 bound methods, 149 class methods, 150 static methods, 151 unbound methods, 148 Class methods, 150 clear() method, 46 Collections module default dictionaries, 49 named tuples, 48 ordered dictionaries, 48 sets add() method, 44 append() method, 44 clear() method, 46 difference() method, 47 discard() method, 45 intersection() method,

2 index Collections module (cont.) issubset() method, 47 issuperset() method, 47 in keyword, 44 letters determination, 43 pop() method, 45 remove() method, 45 union() method, 46 update() method, 44, 46 Comma separated values (CSV) files argument checking column name array, 303 keyword arguments, positional arguments, 301 declarative programming (see Declarative programming) enumerate() method, 304 kwargs, 304 looping, 304 reader() method Content class, 311 csv_dialect attribute, 308 Dialect class, 308 iterable object, 306 iter () method, 309 next () method, row class, reader objects, 300 Row class, 306 writer() method contents, 314 Row subclass, 312 title() method, 313 writerow() method, writer objects, 300 Compatibility policy, backward, Conditional expressions and operator, 34 false value, 35 if/else function, 33 or operator, 34 Context managers, 186 Control flow catching exceptions clause, 24 EnvironmentError, 23 except keyword, 22 IOError, 23 OSError, 23 SystemExit, 23 try keyword, 22 TypeError, 24 conditional expressions and operator, 34 false value, 35 if/else function, 33 or operator, 34 count_lines() function, 28 definition, 22 except blocks, 29 exception chains, 26 optimizing loops, 31 UnicodeDecodeError, 30 with statement, 32 copy() method, 209 CounterMeta class, 290 D Declarative programming advantage, 271 base class, 272 class declaration, 271 end-user code, 272 example.py, 282 fields arguments, 275 attach_to_class() method, 277 base class, 276 columns, 275 definition, 272 init () method, 276 title, 276 init.py module, 282 instance methods, 271 managing options codecs.getreader(), 274 component, 273 custom class, 273 dialects, 275 dictionary implementation, 273 encode() method, 273 header row, 274 init () method, 273 open() function, read() method, 274 validation method, 273 metaclasses attach_to_class() method, 280 class-level attributes, 279 dialect class, 279 encoding, 279 hasattr(), 281 inner class, 279 loop, 281 RowMeta, 281 options container, 272 placeholder, 273 string variable, 270 valuable approach,

3 Index deepcopy () method, 211, 212 del () method, 199 Development Python 3000 development, Python language moratorium, discard() method, 45 Distribution licensing AGPL, 260 BSD license, 261 Free Software Foundation, 262 GPL, 259 LGPL, 261 OSI, 262 online documentation, 267 packaging definition, 262 documentation, MANIFEST.in, 264 sdist command, 265 setup.py, 263 tests directory, 263 PyPI, 267 Django and Elixir approach, 269 doc attribute, 335 Docstrings, 335 indentation, multi-line docstrings, one-line docstrings, 336 using triple double quotes, 336 Doctest module code formatting, 244 docstrings, 243 documentation, 246 print() function, 245 repr() function, 245 testmod() function, 247 times2() function, 247 Documentation comments, 234 docstrings, 235 external installation and configuration, 237 reference documents, 237 tutorials, 237 proper naming, 233 utilities formatting, 238 links, 239 Sphinx, 241 Don t Repeat Yourself (DRY), 13, 22 E elif keyword, 5 enumerate() method, 304 F Field library Column class, DateColumn class format object, 296 strptime() method, 297 to_python() method, DecimalColumn, 295 FloatColumn, 294 IntegerColumn, 294 StringField, 293 to_python() method, 292 to_string() method, 292 Functions annotations annotation_processor, 96 coercion, 98 decorators, 100 typesafe() decorator, 98 type safety, 88 arguments flexibility, 60 get_arguments() function, 72, 74 introspection, 68 invoking functions, 66 keyword, 62 positional arguments, 64 preloading, 67 Python s keyword, 60 required arguments, 64 update() function, 74 values, 69 variable keyword arguments, 66 variable positional, 61 variable positional arguments, 65 decorators arguments, 81 closures, 78 create, 86 log_error() function, 77 memoization, syntax, 77 with/without arguments, 83 wrappers, 79 docstrings, 337 generators, 105 introspection definition, 109 docstrings, 111 modules and packages, 110 object types, 109 lambdas, 107 programming language, 59 functools.partial(),

4 index G, H Garbage collection cyclical references del b, 199 del () method, gc.collect(), 200 gc.module, reference counting, 198 weak reference, 201 General Public License (GPL), 259 getattr () method, 194 get() method, 11 getstate () method, 205 I, J, K import () function, 54 Importing code asterisk, 52 fallback, 50 future module, 51 import () function, 54 importlib module, 56 relative imports, 54 import_module() function, 57 import_path() function, 56 indentation, docstrings, init () method, 253, 258, 276 insort() method, 288 intersection() method, 46 Introspection, 22 issubset() method, 47 issuperset() method, 47 Iterables break statement, 175 built-in range() function, 176 generators, 177 init () method, 175 iter () method, 175 next () method, 175 Iteration category, 19 chaining iterables, 41 definition, 35 dictionary comprehensions, 40 for loop, 36 generator expressions, 39 list comprehensions, 38 looping, 20 memory allocation, 20 object-oriented perspective, 19 range() function, 35 sequence unpacking, 36 set comprehensions, 40 zipping iterables, 42 iter () method, 309 L Lesser General Public License (LGPL), 261 M map() function, 42 Mappings, 184 Memoization, 21 Method resolution order (MRO) base class, 119 breadth-first approach, 122 C3 algorithm, 127 C3 function, 123 candidate class, 123 candidate removal, 125 candidate selection, 126 horizontal approach, 120 non first classes, 124 parent classes, 123 purchase() method, 120 simple two-element list, 122 super() function, test() method, 121, 131 TypeError, 128 while True loop, 124 min() function, 39 N namedtuple() function, 48 Namespace dictionary Borg pattern init () method, 190 new () method, dict attribute, 190 self-caching properties cachedproperty(), getattr () method, 194 ORM, 194 Person.get_employer() method, 195 setattr () method, 194 New BSD license, 261 new () method, 291 next () method, 310 Numbers comparison operations, 174 floor () method, 172 index ()method,

5 Index int () method, 172 round () method, 172 sign operations, 173 TypeError, 171 O Object management deep copy method, 211 garbage collection (see Garbage collection) identity, 189 namespace dictionary (see Namespace dictionary) object type, 189 pickling currency() method, 207 dumps() function, 204 getstate () method, 205 load() and loads() functions, 205 setstate () method, 207 shallow copy, 210 value, 189 Object-Relational Mapping (ORM), 194 open() function, 273 open() method, 274 Open Source Initiative (OSI), 260 Operations bitwise operations, 168 bool () method, 161 mathematical operations arithmetic operations, 163 floor division, 164 floor division vs. true division, 165 modulo operation, 165 pow () method, 167 rectangle, 162 variations, 169 Ordered fields Column. init () attach_to_class(), 288 Column object, 286 Dialect object, 287 init () method, 286, 288 insort() method, 288 RowMeta class, 287 Column. new (), 289 CounterMeta. call (), 290 DeclarativeMeta. prepare () add_column() method, 284 Column class, 285 namespace dictionary, 283 RowMeta, 283 options, 291 or operator, 34 os.stat() function, 324 P, Q Pareto Principle, 15 PEP. See Python Enhancement Proposal (PEP) pop() method, 45 Preloading arguments, 67 Py3k (Python 3000), 343 Python backward compatibility, 16 DRY, 13 keyword arguments, 60 loose coupling, 14 Pareto Principle, 15 Python 3.0, 17 robustness principle, 15 samurai principle, 14 Zen of Python bracket syntax, 11 code blocks, 5 code snippet, 5 comp.lang.python, 1 complexity, 4 documentation, 12 elif keyword, 5 encoding, 11 error handling, 10 explicit code, 3 get() method, 11 implementation, 8, 12 interface, 4 is_valid code, 3 iterative development, 12 keyword arguments, 2 namespace handling, 13 PEP-8, 6 readability Counts, 7 robust error-handling system, 8 Unicode strings, 11 validate() method, 9 Python 3.0, 17, 25 backwards compatibility, 344 language moratorium, Python 3000 development, Python Enhancement Proposal (PEP), 1 PEP 257, 323 (see also Docstrings) PEP 258 (Docutils Design Specification), 336 PEP 361, 343 PEP 3000, 343 PEP 3003 (Python language moratorium), 347, 349 PEP 3099, 343 PEP 3100, 343 Python Package Index (PyPI),

6 index R remove() method, 45 Robustness principle, 15 S Samurai principle, 14 scripts, docstrings, 337 self.fail(), 258 Sequences additional attributes and behaviors, 179 built-in len() function, 179 class range, 183 contains () method, 183 delitem () method, 183 getitem () method, len () method, 179 reversed() function, 180 setitem () method, 182 setattr () method, 194 setstate () method, 207 setup() function, 263 Simplified BSD license, 262 sort() method call, 108 Sphinx, 241 startswith() method, 9 strftime() method, 299 string literals, docstrings, 336 String representation, 158 Strings bytes chr() and ord(), 214 standard strings, 213 struct module, 215 formatting custom format, 230 customizable validation function, 225 explicit format() method, 224 format(), 225 keyword arguments, 224 object reference, 226 plain text table of contents, 228 positional arguments, 224 repr () method, 226 standard format, 226 str () method, 226 simple substitution, 221 text encodings, 219 unicode, 219 strptime() method, 297 Struct module, 215 StudlyCaps, 324 Style guidelines code layout blank lines, 318 encodings (PEP 263), 319 indentation, 318 maximum line length, 318 tabs/spaces, 318 comments, 322 consistency, 317 copyright, 330 documentation strings, 323 expressions and statements, whitespace arithmetic operators, 321 binary operators, 321 compound statements, 322 default parameter value, 321 multiclause statements, 322 pet peeves, 320 imports class-containing module, 320 intrapackage, 319 local application/library-specific, 319 related third-party, 319 separate lines, 319 standard library, 319 naming conventions class names, 325, 328 constants, 326 exception names, 325 function and method arguments, 326 function names, 326 global variable names, 326 method names and instance variables, 326 naming styles, 324 nonpublic attributes, 326 package and module names, 325 public attributes, 326 Pythonic guidelines, 327 subclass API, 327 programming recommendations bare except, 329 catching exceptions, 328 class-based exceptions, 328 isinstance(), 329 None, 328 sequences, 330 startswith() and endswith(), 329 str and unicode, 330 string exceptions, 328 ValueError( message ), 328 version bookkeeping,

7 Index T teardown() method, 257 Testing custom test class, 258 definition, 243 doctest module code formatting, 244 docstrings, 243 documentation, 246 print() function, 245 repr() function, 245 testmod() function, 247 times2() function, 247 test-driven development, 243 unittest module addtypeequalityfunc() method, 253 assertequal(), 252 assertion, 249 AssertionError, 251 assertraises(), assertraisesregexp(), 255 comparison methods, 254 identity, 257 main() function, 250 sequence content, 254 setup() method, 249 strings, 254 teardown() method, 257 TestCase class, 248 tests.py, 250 with block, 256 testnumber() method, 250 tests.py module, 250 title() method, 313 to_python() method, 292 to_string() method, 292 Transparency, 21 U Unbound methods, 148 union() method, 46 Unittest module addtypeequalityfunc() method, 253 assertequal(), 252 assertion, 249 AssertionError, 251 assertraises(), assertraisesregexp(), 255 comparison methods, 254 identity, 257 main() function, 250 sequence content, 254 setup() method, 249 strings, 254 teardown() method, 257 TestCase class, 248 tests.py, 250 with block, 256 update() method, 44, 46 UTF-8, 220 V validate() method, 9 Version compatibility, backward compatibility, Voting guidelines copyright, 331 rationale, 331 voting scores, 331 W What You. See Is What You Get (WYSIWYG), 238 What You. See Is What You Mean (WYSIWYM), 238 writerow() method, 312 writerows() method, 314 X, Y XOR operation, 47 Z Zen of Python, 333 zip() function,