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Python modules should not reinvent OSError

Wandering Thoughts | Aug. 20, 2009, 1:18 a.m. | Original

In light of yesterday's entry , here is one of my newrules for Python modules, especially extension modules written in C:

If you're going to raise an exception because a system call failed,don't make up a new exception for it. Raise either IOError or OSError themselves.

Every deviation from this causes annoyancesfor Python programmers. This is especially visible in the situationwith signals and EINTR , where I really do not want tobe rewriting the same code over and over again with different exception

跋足狂奔的生還者

sopuresotrue | Aug. 19, 2009, 7:03 p.m. | Original

今日是 “workcamp free day“ ，即是義工們在工作營期間的假日。我們在清晨便離開木屋，準備下山去，這是我們第一次下山到市中心去！
在那段下山必經的斜坡，我和另一義工都仆倒了，褲管沾滿了泥濘。我們在國家公園內步行了二個小

極端

silencemo | Aug. 19, 2009, 11:07 a.m. | Original

黑白分明是良好的願望。

小朋友看的卡通片，主角好壞分明，絕不混淆。可是現實世界的人和事，除了黑白兩種色，還有沒有別的顏色？

也許是卡通片看得多了，我們身邊總有一些想法簡單的成年人，誤以為小城的大小事務都是

在森林和原野

sopuresotrue | Aug. 19, 2009, 7:20 a.m. | Original

是的，上文提及那河流就是山下那條可通往北冰洋的葉尼塞河。

需要到山下的河流洗澡可不是令我們一眾人感震撼的主因，背後的食水儲備問題方令我們真正的擔憂起來。原來木屋主人沒想過我們一眾義工需要使用食水，所以他

工作營第一日

sopuresotrue | Aug. 19, 2009, 6:25 a.m. | Original

工作營的俄藉Camp Leader昨夜建議我明早到克拉斯諾亞爾斯克市中心的中央警局報失背包，但俄羅斯警察的官遼風氣甚盛，她着我要有心理準備那可能會折騰大半天。
昨晚我真的完全睡不着，眼光光望天光，整晚想着旅程才剛開始就發

Link: Using colour well in data visualization

Wandering Thoughts | Aug. 19, 2009, 1:18 a.m. | Original

Why Should Engineers and Scientists Be Worried About Color? is abouthow straightforward use of colour in data visualizations can mislead youand hide information (and how to do better). Some of their examplesare eye-opening and alarming.

(Via Hacker News .)

(Since I took up photography I've had a muchincreased interest in how we perceive things, including colour.)

Python, signal handlers, and EINTR

Wandering Thoughts | Aug. 19, 2009, 1:18 a.m. | Original

One of the interesting effects of setting a signal handler inyour Python program is, well, let me quote the signal module :

When a signal arrives during an I/O operation, it is possiblethat the I/O operation raises an exception after the signal handlerreturns. This is dependent on the underlying Unix system's semanticsregarding interrupted system calls.

By 'an I/O operation' the manual means more than you might think; forexample, select.select() is affected by this.