Иногда нужно выполнить блок кода с несколькими менеджерами контекста:
with open('f') as f: with open('g') as g: with open('h') as h: pass
Начиная с Python 2.7 и 3.1, это можно записать в одной конструкции with:
o = open with o('f') as f, o('g') as g, o('h') as h: pass
Раньше для этого использовали функцию contextlib.nested:
with nested(o('f'), o('g'), o('h')) as (f, g, h): pass
Если же число менеджеров контекста заранее неизвестно, лучше подойдёт более продвинутый инструмент. contextlib.ExitStack позволяет открывать любое число контекстов в произвольный момент, но гарантирует корректный выход из них в конце:
with ExitStack() as stack: f = stack.enter_context(o('f')) g = stack.enter_context(o('g')) other = [ stack.enter_context(o(filename)) for filename in filenames ]
Иногда нужно выполнить блок кода с несколькими менеджерами контекста:
with open('f') as f: with open('g') as g: with open('h') as h: pass
Начиная с Python 2.7 и 3.1, это можно записать в одной конструкции with:
o = open with o('f') as f, o('g') as g, o('h') as h: pass
Раньше для этого использовали функцию contextlib.nested:
with nested(o('f'), o('g'), o('h')) as (f, g, h): pass
Если же число менеджеров контекста заранее неизвестно, лучше подойдёт более продвинутый инструмент. contextlib.ExitStack позволяет открывать любое число контекстов в произвольный момент, но гарантирует корректный выход из них в конце:
with ExitStack() as stack: f = stack.enter_context(o('f')) g = stack.enter_context(o('g')) other = [ stack.enter_context(o(filename)) for filename in filenames ]
Bitcoin is a decentralized digital currency that you can buy, sell and exchange directly, without an intermediary like a bank. Bitcoin’s creator, Satoshi Nakamoto, originally described the need for “an electronic payment system based on cryptographic proof instead of trust.” Each and every Bitcoin transaction that’s ever been made exists on a public ledger accessible to everyone, making transactions hard to reverse and difficult to fake. That’s by design: Core to their decentralized nature, Bitcoins aren’t backed by the government or any issuing institution, and there’s nothing to guarantee their value besides the proof baked in the heart of the system. “The reason why it’s worth money is simply because we, as people, decided it has value—same as gold,” says Anton Mozgovoy, co-founder & CEO of digital financial service company Holyheld.
Telegram and Signal Havens for Right-Wing Extremists
Since the violent storming of Capitol Hill and subsequent ban of former U.S. President Donald Trump from Facebook and Twitter, the removal of Parler from Amazon’s servers, and the de-platforming of incendiary right-wing content, messaging services Telegram and Signal have seen a deluge of new users. In January alone, Telegram reported 90 million new accounts. Its founder, Pavel Durov, described this as “the largest digital migration in human history.” Signal reportedly doubled its user base to 40 million people and became the most downloaded app in 70 countries. The two services rely on encryption to protect the privacy of user communication, which has made them popular with protesters seeking to conceal their identities against repressive governments in places like Belarus, Hong Kong, and Iran. But the same encryption technology has also made them a favored communication tool for criminals and terrorist groups, including al Qaeda and the Islamic State.
Библиотека Python разработчика | Книги по питону from jp
