Python Distilled

Welcome! This repo contains errata related to the Python Distilled book by David Beazley. If you'd like to contribute, please submit an issue or pull request.

Errata

• Table 1.2, pg. 5. Description for round(a, [n]) should state that it rounds to the nearest multiple of 10 to the -nth power.

• Section 1.6, pg. 10. Comment in code sample mid-page should read # g = 'Hello Cruel World'.

• Table 1.6, pg. 10. Description for s.endswith(prefix [,start [,end]]) would be better if it used suffix instead of prefix.

• Section 1.8, pg. 15. ['SYM', '123', '456.78'] should include the newline and be ['SYM', '123', '456.78\n']

• Section 1.10, pg. 17-18. There is somewhat inconsistent use of variable names in this section. The names1 variable should be s and the names2 variable should be t.

• Section 1.15, pg. 26. print "Going away..." should be print("Going away...")

• Section 2.1, pg. 38. Typo mid-page should read "Tuple, list, set, and dictionary literals are written as follows:"

• Section 2.7, pg. 43. Truthiness should be expanded to include sets and any non-empty container. "... any nonzero number, a nonempty string, list, tuple, set, dictionary, or container is taken to be true."

• Section 2.7, pg. 44. The function invocation of foo(3, a) should be f(3, a).

• Section 2.14, pg. 52. The list comprehension example should use squares instead of nums.

nums = [1, 2, 3, 4, 5]
squares = [ ]
for n in nums:
    squares.append(n*n)

• Section 2.15, pg. 55. The code example should use slicing t[:1] instead of indexing t[0] to avoid a possible IndexError exception.

comments = (t for t in lines if t[:1] == '#')   # All comments

• Section 4.8, pg. 88. compute_cost(prices, quantities) should be compute_cost(prices, units).

• Section 5.8, pg. 106. The docstring in the factorial() function should use factorial(5) instead of factorial(6) to get a result of 120.

• Section 5.16, pg. 121. The first function signature for after() should be changed to the following:

def after(seconds, func, /, *args, debug=False, **kwargs):
    ...

• Section 6.4, pg. 145. The code for print_matching() should be as follows:

def print_matching(lines, substring):
    for line in lines:
        if substring in line:     # line instead of lines
	    print(substring)

• Section 7.1, pg. 153. An extra line should probably be added to the example to show the effect of mutation:

>>> names[1] = 'Tom'
>>> names
[ 'Paula', 'Tom', 'Lewis' ]
>>>

• Section 7.3, pg. 156. Missing right parenthesis on b.withdraw(50.0).

• Section 7.7, pg. 160. Perhaps the class should be called MyAccount instead of MyAcount. Although, it's inheritance--you can call the class whatever you want!

• Section 7.12, pg. 172. Comment in code right before section 7.13 should read # Calls Date.today(Date).

• Section 7.21, pg. 194. The code for register_decoder() should use mt instead of mt.mimetype. For example:

_registry = { }
def register_decoder(cls):
    for mt in cls.mimetypes:
        _registry[mt] = cls
    return cls

• Section 7.23, pg. 200. Typo in constructor example at the top. Should be

a = Account.__new__(Account, 'Guido', 1000.0)
if isinstance(a, Account):
    a.__init__('Guido', 1000.0)

The example that follows should also be corrected to:

a = Account.__new__(Account)
a.__init__('Guido', 1000.0)

• Section 7.23, pg. 200. Typos in the date today() constructor. Should be

@classmethod
def today(cls):
    t = time.localtime()
    self = cls.__new__(cls)    # Make instance
    self.year = t.tm_year
    self.month = t.tm_mon
    self.day = t.tm_mday
    return self

• Section 7.23, pg. 201. NOT a typo. The __new__() method of a class is, in fact, properly defined as a @staticmethod even though it looks like it ought to be a class method. This is strange, but you can see this in examples where __new__() is invoked directly. For example, a = Account.__new__(Account) on the previous page. Here, Account is passed directly as the cls argument as would be required with a @staticmethod.

• Section 7.26, pg. 208. Typo (missing "that"). "A proxy is an object that exposes..."

• Section 7.28, pg. 212. del f.owner should be del a.owner in example.

• Section 8.7, pg. 234. It should be noted that the PYTHONPATH environment variable is a colon-separated list of paths.

• Section 8.14, pg. 241. Typo ("is" should be "if"). "For example, if your package looks like this:"

• Section 9.3, pg. 250. format(x, '<*10.2f') should be format(x, '*<10.2f').

• Section 9.3, pg. 250. "The general format of the format specifier should be [fill][align][sign][0][width][,][.precision][type] where each part enclosed in [] is optional."

• Section 9.3, pg, 252. 'Value is {val:<*10.2f}'.format(val=x) should be 'Value is {val:*<10.2f}'.format(val=x).

• Section 9.3, pg, 253. Comment in code sample at bottom third of the page should be changed from # b'The value is 123.46' to # b'Value is 123.46'.

• Section 9.9, pg. 264. for filename in path.Path('dirname').glob('*.txt') should be for filename in pathlib.Path('dirname').glob('*.txt').

• Section 9.15.9, pg. 279. Typo, missing "to" in the sentence "Go to a directory with a collection of files and type the following:"

• Section 9.15.12, pg. 281. Typo in code comment ("one" should be "once").

# Configuration of logging (occurs once at program startup)

• Section 9.15.15, pg. 283. There is an extra return pathname.stat().st_size statement that can be removed (because there is a return statement right above it).

• Section 9.15.19, pg. 285. serv should be server in the SMTP example:

server = smtplib.SMTP('localhost')
server.sendmail(fromaddr, toaddrs, msg)
server.quit()

• Section 9.15.21, pg. 288. The output of struct.pack() should be as follows:

>>> struct.pack(">HIff", 123, 456, 1.23, 4.56)
b'\x00{\x00\x00\x01\xc8?\x9dp\xa4@\x91\xeb\x85'
>>>

• Section 10.1, pg. 308. The description of round() should start with "Returns the result of rounding the floating-point number..."

• Table 10.9, pg. 311. The description for format_map() should use "taken" instead of "taking". "Formats s with substitutions taken from the mapping m."

• Table 10.10, pg. The description for s + t should read "Concatenation if t is a tuple."

• Table 10.10, pg, 313. The s.append(x) method should be deleted.

Acknowledgements

The following individuals have contributed errata:

• Jonathan Oberländer
• Lucas Plaetevoet
• Chris Gibson
• Lawrence Wu
• Andy Lester
• Siavash Tavakoli
• Said van de Klundert
• David Dyck
• Scythal
• Feng Guo
• Xavier Noria
• Evan Friedenberg
• Karthik-d-k
• Marc Hertzog
• Jack Rubin
• Paul Barry
• @physadair
• @phils4000
• @michrag
• Sam Kramer
• @wildekat
• Shivam Parke
• Olivia Nelson
• @occoder
• @yatcui