Регулярные выражения в python от простого к сложному. подробности, примеры, картинки, упражнения

Registering a Concrete Class¶

There are two ways to indicate that a concrete class implements an
abstract: register the class with the abc or subclass directly from
the abc.

import abc
from abc_base import PluginBase

class RegisteredImplementation(object):
    def load(self, input):
        return input.read()
    def save(self, output, data):
        return output.write(data)


if __name__ == '__main__'
    print 'Subclass:', issubclass(RegisteredImplementation, PluginBase)
    print 'Instance:', isinstance(RegisteredImplementation(), PluginBase)

In this example the PluginImplementation is not derived from
PluginBase, but is registered as implementing the PluginBase

Целочисленные константы

Python поддерживает целочисленные строковые константы в различных системах счисления — восьмеричной, десятичной (конечно же!) и шестнадцатеричной, — а теперь к ним добавилась и двоичная. Изменилось представление констант в восьмеричной системе: теперь они начинаются префиксом или (т.е. ноль и за ним маленькая или большая буква «o») и затем значение константы. Например восьмеричное 13 или десятичное 11 представляется так:


Новые двоичные константы начинаются префиксом
или (т.е. ноль и за ним маленькая или большая «b»). Десятичное 21 в двоичном виде представляется так:


Методы и были удалены.

Altre Raccolte

Di seguito sono elencate altre raccolte di link a documentazione relativa a Python.
In questi elenchi possono essere trovati approfondimenti e documentazione relativa a specifiche librerie o framework (Django, Flask, Kivy, Pandas, Pyramid. Tornado, …)

      • Packt Publishing: Free Learning — Free Programming Ebooks
      • O’Reilly Media: Free Ebooks
      • Syncfusion: Succinctly free eBooks
      • Awesome Python — una lista di frameworks, librerie e software

Ogni contributo è ben accetto, leggi il codice di condotta e la pagina con le linee guida alla collaborazione.

Questa guida è è pubblicata con licenza CC BY 4.0 (Creative Commons Attribution 4.0 International) — leggi qui i dettagli.

ABCs vs. Interfaces

ABCs are not intrinsically incompatible with Interfaces, but there is
considerable overlap. For now, I’ll leave it to proponents of
Interfaces to explain why Interfaces are better. I expect that much
of the work that went into e.g. defining the various shades of
«mapping-ness» and the nomenclature could easily be adapted for a
proposal to use Interfaces instead of ABCs.

«Interfaces» in this context refers to a set of proposals for
additional metadata elements attached to a class which are not part of
the regular class hierarchy, but do allow for certain types of
inheritance testing.

Such metadata would be designed, at least in some proposals, so as to
be easily mutable by an application, allowing application writers to
override the normal classification of an object.

The drawback to this idea of attaching mutable metadata to a class is
that classes are shared state, and mutating them may lead to conflicts
of intent. Additionally, the need to override the classification of
an object can be done more cleanly using generic functions: In the
simplest case, one can define a «category membership» generic function
that simply returns False in the base implementation, and then provide
overrides that return True for any classes of interest.

String Special Operators

Assume string variable a holds ‘Hello’ and variable b holds ‘Python’, then −

Operator Description Example
+ Concatenation — Adds values on either side of the operator a + b will give HelloPython
* Repetition — Creates new strings, concatenating multiple copies of the same
a*2 will give -HelloHello
[] Slice — Gives the character from the given index a will give e
Range Slice — Gives the characters from the given range a will give ell
in Membership — Returns true if a character exists in the given string H in a will give 1
not in Membership — Returns true if a character does not exist in the given string M not in a will give 1
r/R Raw String — Suppresses actual meaning of Escape characters. The syntax for raw strings is exactly the same as for normal strings with the exception of the raw string operator, the letter «r,» which precedes the quotation marks. The «r» can be lowercase (r) or uppercase (R) and must be placed immediately preceding the first quote mark. print r’\n’ prints \n and print R’\n’prints \n
% Format — Performs String formatting See at next section
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