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What is a NullPointerException, and how do I fix it?
What are Null Pointer Exceptions ( java.lang.NullPointerException ) and what causes them?
12 Answers
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How efficient is locking an unlocked mutex? What is the cost of a mutex?
...bunch of mutexes or a single one for an object.
If you have many threads and the access to the object happens often, then multiple locks would increase parallelism. At the cost of maintainability, since more locking means more debugging of the locking.
How efficient is it to lock a mutex? I.e....
A cron job for rails: best practices?
...Listener.process_new_messages
puts "done."
end
To execute from the command line, this is just "rake cron". This command can then be put on the operating system cron/task scheduler as desired.
Update this is quite an old question and answer! Some new info:
the heroku cron service I referenced ...
Convert a list of data frames into one data frame
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since it's 2018 and dplyr is both fast and a solid tool to use, I've changed this to the accepted answer. The years, they fly by!
– JD Long
Jan 12 '19 at 12:03
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Git cherry pick vs rebase
...-one.
Hence, possibly the most striking difference between these two commands is how they treat the branch they work on: git cherry-pick usually brings a commit from somewhere else and applies it on top of your current branch, recording a new commit, while git rebase takes your current branch and ...
serve current directory from command line
could someone give me a hint, howto serve the current directory from command line with ruby? it would be great, if i can have some system wide configuration (e.g. mime-types) and simply launch it from every directory.
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How to create an infinite loop in Windows batch file?
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And from cmd prompt?
– theonlygusti
Mar 13 '15 at 16:11
13
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Can't use Swift classes inside Objective-C
...try to integrate Swift code in my app.My app is written in Objective-C and I added a Swift class. I've done everything described here . But my problem is that Xcode haven't created the -Swift.h file, only the bridging headers. So I created it, but it's actually empty.
I can use all my Obj...
C++应用程序添加VBScript和JavaScript支持 - C/C++ - 清泛网 - 专注IT技能提升
C++应用程序添加VBScript和JavaScript支持Adding-VBScript-and-JavaScript-support-in-Cpp-applC++ VBScript JavaScript 支持采用MSSCRIPT.OCX在C++程序中调用JavaScript及VBScript。效果截图：
源码点此下载。
Introduction
I am always amazed to see how the script control (m...
C++应用程序添加VBScript和JavaScript支持 - C/C++ - 清泛网 - 专注IT技能提升
C++应用程序添加VBScript和JavaScript支持Adding-VBScript-and-JavaScript-support-in-Cpp-applC++ VBScript JavaScript 支持采用MSSCRIPT.OCX在C++程序中调用JavaScript及VBScript。效果截图：
源码点此下载。
Introduction
I am always amazed to see how the script control (m...