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Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?
...ich is allowed to vary down as the class is subtyped (alternatively, vary with subtyping, hence the "co-" prefix). More concretely:
trait List[+A]
List[Int] is a subtype of List[AnyVal] because Int is a subtype of AnyVal. This means that you may provide an instance of List[Int] when a value of ...
Git rebase: conflicts keep blocking progress
I have a git branch (called v4), that was made from master just yesterday. There were a couple of changes to master, that I want to get into v4. So, in v4, I tried to do a rebase from master, and one file keeps screwing things up: a one-line text file, that contains the version number. This file ...
Cancel split window in Vim
I have split my windows horizontally. Now how can I return to normal mode, i.e. no split window just one window without cancelling all of my open windows. I have 5 and do not want to "quit", just want to get out of split window.
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Difference between IsNullOrEmpty and IsNullOrWhiteSpace in C# [duplicate]
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Source: MSDN
IsNullOrWhiteSpace is a convenience method that is similar to the
following code, except that it offers superior performance:
return String.IsNullOrEmpty(value) || value.Trim().Length == 0;
White-space characters are defined b...
Why should I use Hamcrest-Matcher and assertThat() instead of traditional assertXXX()-Methods
...alue") && foo.contains("anotherValue"));
vs.
assertThat(foo, hasItems("someValue", "anotherValue"));
One can discuss which one of those is easier to read, but once the assert fails, you'll get a good error message from assertThat, but only a very minimal amount of information from asser...
How to declare a type as nullable in TypeScript?
...SomeEmployeeB implements Employee1 {
public name: string;
}
Compare with:
interface Employee2 {
name: string;
salary?: number;
}
var a: Employee2 = { name: 'Bob', salary: 40000 }; // OK
var b: Employee2 = { name: 'Bob' }; // OK
var c: Employee2 = { name: 'Bob', salary: undefined }; /...
How do I change the UUID of a virtual disk?
I am trying to create a new virtual machine with Oracle VirtualBox, using an already-existing hard disk. When I try to select the existing hard disk file, a .vhd file, it displays an error saying the virtual hard disk cannot be used because the UUID already exists.
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How to write PNG image to string with the PIL?
I have generated an image using PIL . How can I save it to a string in memory?
The Image.save() method requires a file.
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Cannot find Dumpbin.exe
... Visual Studio 2005 on my system. When I type dumpbin on the command line, it says unrecognizable command.
9 Answers
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How to select between brackets (or quotes or …) in Vim?
...m sure there used to be a plugin for this kinda stuff, but now that I need it, I can't seem to find it (naturally), so I'll just ask nice and simple.
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