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How to upgrade PostgreSQL from version 9.6 to version 10.1 without losing data?
...5433 (the standard default is 5432), so keep this in mind if attempting to test the new instance before "cutting-over" to it.
Start the server as normal (again, this will start both the old and new instances):
systemctl start postgresql
If you want to make the new version the default, you will n...
Why is rbindlist “better” than rbind?
...Try DF = data.frame(a=1:3); .Internal(inspect(DF)); tracemem(DF); attr(DF,"test") <- "hello"; .Internal(inspect(DF)).
– Matt Dowle
Mar 28 '13 at 13:38
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Android static object lifecycle
...uld any of the above three happen the static will lose its value.
You can test this with a few lines of code:
print the uninitialized static in onCreate of your activity -> should print null
initialize the static. print it -> value would be non null
Hit the back button and go to home screen...
Custom attributes in styles.xml
...d to point out that @vince's explanation may not be entirely accurate.
To test the hypothesis that the name attribute of the declare-styleable matching the name of the custom view class is allowing us to access the custom attribute without a namespace I changed the name of the declare-styleable (th...
What is the purpose of the “Prefer 32-bit” setting in Visual Studio and how does it actually work?
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@RanSagy you can simply test it by creating a new project and checking Project -> Properties -> Build tab -> Platform target... but note that AnyCPU-32bitPreferred is only available in .Net version 4.5 and higher. That's why the default is ...
Why do we need a pure virtual destructor in C++?
...ng of base class without making any change in your already implemented and tested derive class, you implement a pure virtual destructor in your base class.
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Are the shift operators () arithmetic or logical in C?
...ements an arithmetic shift on signed values.
Basically you need to either test your compiler or not rely on it. My VS2008 help for the current MS C++ compiler says that their compiler does an arithmetic shift.
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Good examples of MVVM Template
...t this way seems more straightforward than working around it. Easy to unit test as well.
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ES6 class variable alternatives
... return this.constructor.foo;
}
}
MyClass.foo = 'bar';
I've only tested this with Traceur, but I believe it will work the same in a standard implementation.
JavaScript doesn't really have classes. Even with ES6 we're looking at an object- or prototype-based language rather than a class-ba...
Why use Ruby's attr_accessor, attr_reader and attr_writer?
...kes 94% of the time that the manually defined accessor does. In all of my tests, however, accessors are fast: an accessor takes about 820 nanoseconds (Ruby 1.8.7) or 440 nanoseconds (Ruby 1.9). At those speeds, you'll need to call an accessor hundreds of millions of times for the performance bene...