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What are the effects of exceptions on performance in Java?
...e hit. The problem with this kind of test is that it encourages people to stop using exceptions altogether. Using exceptions, for exceptional case handling, performs vastly better than what your test shows.
– Nate
Apr 1 '14 at 0:53
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Grouping functions (tapply, by, aggregate) and the *apply family
...ck, rather than a list.
If you find yourself typing unlist(lapply(...)), stop and consider
sapply.
x <- list(a = 1, b = 1:3, c = 10:100)
# Compare with above; a named vector, not a list
sapply(x, FUN = length)
a b c
1 3 91
sapply(x, FUN = sum)
a b c
1 6 5005
In more...
Delete newline in Vim
...ne in normal mode, hit Shift+j.
You can prepend a count too, so 3J on the top line would join all those lines together.
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iPhone: Setting Navigation Bar Title
...
...
[bar pushNavigationItem:item animated:YES];
[item release];
or
bar.topItem.title = @"title text";
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How to find the width of a div using vanilla JavaScript?
...styles of that elements. For example: padding, paddingLeft, margin, border-top-left-radius and so on.
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Why are #ifndef and #define used in C++ header files?
... the file has been included and checking that the token was not set at the top of that file.
#ifndef _INCL_GUARD
#define _INCL_GUARD
#endif
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Why is TypedReference behind the scenes? It's so fast and safe… almost magical!
... not necessarily trivial/possible for C# implementations that don't run on top of a CLI at all or run on top of a CLI without Varargs.
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Eclipse: enable assertions
...for all JUnit tests then go to Preferences > Java > JUnit and at the top click the checkbox for "Add 'ea' to VM arguments when creating new JUnit launch configuration" Now Eclipse won't bug you for every new test you want to run. For existing tests you have to remove their's run configurations...
What Haskell representation is recommended for 2D, unboxed pixel arrays with millions of pixels?
... very limited range of ready to use matrix and array algorithms written on top of it, but at least it is possible to express important algorithms by the means of the library. For example, there are already routines for matrix multiplication and for convolution in repa-algorithms. Unfortunately, it s...
App Inventor 2 低功耗蓝牙 BlueToothLE 拓展 · App Inventor 2 中文网
...) —
在读取或注册调用中传递的服务UUID。
StopAdvertising – 停止蓝牙低功耗广播（之前调用 StartAdvertising 的广播）。
StartScanning – 开始扫描蓝牙低功耗设备。
StopScanning – 停止扫描蓝牙低功...