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Why shouldn't Java enum literals be able to have generic type parameters?
Java enums are great. So are generics. Of course we all know the limitations of the latter because of type erasure. But there is one thing I don't understand, Why can't I create an enum like this:
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How are booleans formatted in Strings in Python?
...False)
True, False
This is not specific to boolean values - %r calls the __repr__ method on the argument. %s (for str) should also work.
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MVC (Laravel) where to add logic
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I think all patterns / architectures that you present are very useful as long as you follow the SOLID principles.
For the where to add logic I think that it's important to refer to the Single Responsibility Principle. Also, my answe...
Is it bad practice to have a constructor function return a Promise?
...create and initialize a new instance. It should set up data structures and all instance-specific properties, but not execute any tasks. It should be a pure function without side effects if possible, with all the benefits that has.
What if I want to execute things from my constructor?
That shou...
How to atomically delete keys matching a pattern using Redis
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Starting with redis 2.6.0, you can run lua scripts, which execute atomically. I have never written one, but I think it would look something like this
EVAL "return redis.call('del', unpack(redis.call('keys', ARGV[1])))" 0 prefix:[YOUR_PREFIX e.g delete_me_*]
Warning: As the Redis document sa...
Best way to represent a fraction in Java?
...ompareTo(denominator.multiply(f.numerator));
}
/**
* Returns the smaller of this and f.
*/
public BigFraction min(BigFraction f)
{
if(f == null)
throw new IllegalArgumentException("Null argument");
return (this.compareTo(f) <= 0 ? this : f);
}
/**
* Returns t...
MySQL INSERT INTO table VALUES.. vs INSERT INTO table SET
...
I think the extension is intended to allow a similar syntax for inserts and updates. In Oracle, a similar syntactical trick is:
UPDATE table SET (col1, col2) = (SELECT val1, val2 FROM dual)
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JPA EntityManager: Why use persist() over merge()?
...ed (any changes you make will not be part of the transaction - unless you call merge again). You can through use returned instance (managed one).
Maybe a code example will help.
MyEntity e = new MyEntity();
// scenario 1
// tran starts
em.persist(e);
e.setSomeField(someValue);
// tran ends, an...
Why wasn't PyPy included in standard Python?
...e JIT compilation and lower memory footprint greatly improve the speeds of all Python code?
6 Answers
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promise already under evaluation: recursive default argument reference or earlier problems?
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Formal arguments of the form x=x cause this. Eliminating the two instances where they occur we get:
f <- function(x, T) {
10 * sin(0.3 * x) * sin(1.3 * x^2) + 0.001 * x^3 + 0.2 * x + 80
}
g <- function(x, T, f. = f) { ## 1. note f.
exp(-...