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When should I use the Visitor Design Pattern? [closed]
I keep seeing references to the visitor pattern in blogs but I've got to admit, I just don't get it. I read the wikipedia article for the pattern and I understand its mechanics but I'm still confused as to when I'd use it.
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Break promise chain and call a function based on the step in the chain where it is broken (rejected)
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The reason your code doesn't work as expected is that it's actually doing something different from what you think it does.
Let's say you have something like the following:
stepOne()
.then(stepTwo, handleErrorOne)
.then(stepThree, handleErrorTwo)
.then(null, handleErrorThree);
...
How to make git mark a deleted and a new file as a file move?
I've moved a file manually and then I've modified it. According to Git, it is a new file and a removed file. Is there any way to force Git into treating it as a file move?
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How to get a Fragment to remove itself, i.e. its equivalent of finish()?
I'm converting an app to use fragments using the compatibility library.
Now currently I have a number of activities (A B C D) which chain onto one another, D has a button 'OK' which when pressed calls finish which then bubbles up through onActivityResult() to additionally destroy C and B.
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JavaScript curry: what are the practical applications?
I don’t think I’ve grokked currying yet. I understand what it does, and how to do it. I just can’t think of a situation I would use it.
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Can't operator == be applied to generic types in C#?
...e compiler can't make that assumption.
However, this will compile because it is more explicit:
bool Compare<T>(T x, T y) where T : class
{
return x == y;
}
Follow up to additional question, "But, in case I'm using a reference type, would the the == operator use the pred...
Include jQuery in the JavaScript Console
... there an easy way to include jQuery in the Chrome JavaScript console for sites that do not use it? For example, on a website I would like to get the number of rows in a table. I know this is really easy with jQuery.
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Convert java.util.Date to java.time.LocalDate
...Instant().atZone(ZoneId.systemDefault()).toLocalDate();
Explanation
Despite its name, java.util.Date represents an instant on the time-line, not a "date". The actual data stored within the object is a long count of milliseconds since 1970-01-01T00:00Z (midnight at the start of 1970 GMT/UTC).
The...
Why must wait() always be in synchronized block
We all know that in order to invoke Object.wait() , this call must be placed in synchronized block, otherwise an IllegalMonitorStateException is thrown. But what's the reason for making this restriction? I know that wait() releases the monitor, but why do we need to explicitly acquire the mon...
Concurrent vs serial queues in GCD
...A simple example: you have a block that takes a minute to execute. You add it to a queue from the main thread. Let's look at the four cases.
async - concurrent: the code runs on a background thread. Control returns immediately to the main thread (and UI). The block can't assume that it's the only ...