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Checking if a variable is defined?
...ned? keyword (documentation). It will return a String with the kind of the item, or nil if it doesn’t exist.
>> a = 1
=> 1
>> defined? a
=> "local-variable"
>> defined? b
=> nil
>> defined? nil
=> "nil"
>> defined? String
=> "constant"
>> de...
Android代码优化小技巧 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...copy实现的9倍多。
Tip: Also see Josh Bloch’s Effective Java, item 47.
谨慎使用native函数
当你需要把已经存在的native code迁移到Android，请谨慎使用JNI。如果你要使用JNI,请学习JNI Tips
关于性能的误区
在没有做JIT之前，使用一种确切的...
Convert array of strings into a string in Java
...cause you're creating and throwing away as many string objects as you have items in your array. For small arrays you might not really notice the difference, but for large ones it can be orders of magnitude slower.
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How to create a Menubar application for Mac
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NSStatusItem is what you are looking for. Also add LSUIElement with string value of 1 to your Info.plist to hide it from Dock.
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get list of pandas dataframe columns based on data type
...64'): ['B'], dtype('O'): ['C', 'D']}
>>> {k.name: v for k, v in g.items()}
{'object': ['C', 'D'], 'int64': ['A', 'E'], 'float64': ['B']}
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Using C# to check if string contains a string in string array
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how to get which item in the array matched?
– ibubi
Oct 25 '17 at 8:33
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How to install multiple python packages at once using pip
...
and in the requirements.txt file you put your modules in a list, with one item per line.
Django=1.3.1
South>=0.7
django-debug-toolbar
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How stable is the git plugin for eclipse?
...s somehow does not work for Snow Leopard running Eclipse (64-bit). The Git item does not show up in the Import menu or anywhere. :-(
– TraderJoeChicago
Mar 17 '10 at 4:17
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C++ catch blocks - catch exception by value or reference? [duplicate]
...another type MyException which inherits from CustomException and overrides items like an error code. If a MyException type was thrown your catch block would cause it to be converted to a CustomException instance which would cause the error code to change.
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Cannot set boolean values in LocalStorage?
...§11.9.3 “The Abstract Equality Comparison Algorithm”)
Edit: The setItem interface was reverted to accept strings only on the 2011 Sept 1st draft to match the behavior of existing implementations, as none of the vendors are interested in supporting storing non-strings. See https://www.w3.org/...