The Old Reader

11 Apr 19:00

The story of how a nun played private equity's game and created affordable housing in the Bay Area

Bay Area Justin Sullivan/Getty Images

Conor Dougherty is an economics reporter at The New York Times. He previously spent a decade in New York covering housing and the economy for The Wall Street Journal. He grew up in the Bay Area and lives with his family in Oakland.
The following is an excerpt from his new book, "GOLDEN GATES: Fighting for Housing in America."
In it, he tells the story of Sister Christina, a nun who runs the Catholic nonprofit St. Francis Center and presides over a portfolio of 10 buildings with 87 apartments.
Sister Christina purchases buildings with money from foundations, corporations, and other sources, and then deed restricts them as affordable forever.
In this instance, the building right across the street from St. Francis was being sold — and Sister Christina was eventually able to buy it.
Visit Business Insider's homepage for more stories.

Sister Christina was sitting at her desk, next to a bookcase decorated with pictures of smiling children and a woodcut that read "Peace," when a call from private equity intruded in her life. Sister Christina Heltsley was a nun who ran a Catholic nonprofit called the St. Francis Center, which sat in North Fair Oaks, an unincorporated piece of San Mateo County just a few miles from Facebook's headquarters.

The call was from a man who worked for a Los Angeles private equity firm called Trion Properties. He said his company had just bought the building across the street from her — a 48-unit apartment complex called the Buckingham Apartments. It was one of the largest buildings in the vicinity and home to dozens of low-income Latino families who depended on St. Francis's food pantry, clothing donations, and immigration counseling, and sent their kids to an adjoining school. See the rest of the story at Business Insider

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25 Dec 13:15

Python3.6正式版要来了，你期待哪些新特性？

by 笑虎

按照Python官网上的计划，Python3.6正式版期望在2016-12-16号发布，也就是这周五。从去年的5月份开始，Python3.6版本就已经动手开发了，期间也断断续续的发布了4个Alpha版，4个Beta版，以及一个Candidate版本。

作为一个Python爱好者，很期待新版本的发布，也希望能第一时间尝试一下新特性。本文就根据Python官网文章What’s New In Python 3.6，简单介绍下Python3.6中的一些新特性。

如果你想尝试Python3.6，又不想破坏本机的Python环境，建议使用Docker。如果不会使用Docker，建议阅读下专栏中文章：只要一小时，零基础入门Docker

还是来规矩，所有代码上传至Github：xianhu/LearnPython

新的语法特性

1、格式化字符串（Formatted string literals）

即在普通字符串前添加 f 或 F 前缀，其效果类似于str.format()。比如

name = "Fred"
print(f"He said his name is {name}.")  # 'He said his name is Fred.'

其效果相当于：

print("He said his name is {name}.".format(**locals()))

此外，此特性还支持嵌套字段，比如：

width = 10
precision = 4
value = decimal.Decimal("12.34567")
print(f"result: {value:{width}.{precision}}")  #'result:      12.35'

2、变量声明语法（variable annotations）

即从Python3.5开始就有的Typehints。在Python3.5中，是这么使用的：

from typing import List

def test(a: List[int], b: int) -> int:
    return a[0] + b

print(test([3, 1], 2))

这里的语法检查只在编辑器（比如Pycharm）中产生，在实际的使用中，并不进行严格检查。

在Python3.6中，引入了新的语法：

from typing import List, Dict

primes: List[int] = []
captain: str    # 此时没有初始值

class Starship:
    stats: Dict[str, int] = {}

3、数字的下划线写法（Underscores in Numeric Literals）

即允许在数字中使用下划线，以提高多位数字的可读性。

a = 1_000_000_000_000_000       # 1000000000000000
b = 0x_FF_FF_FF_FF              # 4294967295

除此之外，“字符串格式化”也支持“_”选项，以打印出更易读的数字字符串：

'{:_}'.format(1000000)          # '1_000_000'
'{:_x}'.format(0xFFFFFFFF)      # 'ffff_ffff'

4、异步生成器（Asynchronous Generators）

在Python3.5中，引入了新的语法 async 和 await 来实现协同程序。但是有个限制，不能在同一个函数体内同时使用 yield 和 await，在Python3.6中，这个限制被放开了，Python3.6中允许定义异步生成器：

async def ticker(delay, to):
"""Yield numbers from 0 to *to* every *delay* seconds."""
    for i in range(to):
        yield i
        await asyncio.sleep(delay)

5、异步解析器（Asynchronous Comprehensions）

即允许在列表list、集合set 和字典dict 解析器中使用 async for 或 await 语法。

result = [i async for i in aiter() if i % 2]
result = [await fun() for fun in funcs if await condition()]

新增加模块

Python标准库（The Standard Library）中增加了一个新的模块：secrets。该模块用来生成一些安全性更高的随机数，以用来管理数据，比如passwords, account authentication, security tokens, 以及related secrets等。具体用法可参考官方文档：secrets