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Why is XOR the default way to combine hashes?
...d thing, but xor is a lousy choice even then because all pairs of matching items will get hashed to zero. An arithmetic sum is better; the hash of a pair of matching items will retain only 31 bits of useful data rather than 32, but that's a lot better than retaining zero. Another option may be to ...
What's an elegant way to conditionally add a class to an HTML element in a view?
...to conditionally apply class names
in views.
Before:
<div class="<%= item.for_sale? ? 'active' : '' %>">
After:
<div class="<%= class_names(active: item.for_sale?) %>">
More examples:
class_names("foo", "bar")
# => "foo bar"
class_names({ foo: true, bar: false })
# =>...
Referring to the null object in Python
...
In Python, the 'null' object is the singleton None.
The best way to check things for "Noneness" is to use the identity operator, is:
if foo is None:
...
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Are arrays passed by value or passed by reference in Java? [duplicate]
...d yet?). Quick example:
// assuming you allocated the list
public void addItem(Integer[] list, int item) {
list[1] = item;
}
You will see the changes to the list from the calling code. However you can't change the reference itself, since it's passed by value:
// assuming you allocated the li...
What do (lambda) function closures capture?
... that uses your array-indexing syntax:
class Adders(object):
def __getitem__(self, item):
return lambda a: a + item
adders = Adders()
adders[1](3)
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What is array to pointer decay?
...ed in an expression, it is automatically converted to a pointer to the 1st item in the array.
Note that function names act in a similar way, but function pointers are used far less and in a much more specialized way that it doesn't cause nearly as much confusion as the automatic conversion of array...
C++ valarray vs. vector
...imensional array. You also get mask_array to "mask" an operation (e.g. add items in x to y, but only at the positions where z is non-zero). To make more than trivial use of valarray, you have to learn a lot about these ancillary classes, some of which are pretty complex and none of which seems (at l...
What is the most effective way for float and double comparison?
...bly still valid, and the code is nice, but some people found improvements. Best go get the latest version of AlmostEquals right from the Google Test source code, and not the one I pasted up here.
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Select multiple records based on list of Id's with linq
...n't have to explicitly write == anywhere when you're trying to compare the items of one set (the array) against another (the database table).
– Yuck
May 29 '13 at 22:00
...
jQuery - get a list of values of an attribute from elements of a class
...tributeName) {
var results = [];
$.each(this, function (i, item) {
results.push(item.getAttribute(attributeName));
});
return results;
}
});
Now you can get the list of level values by calling:
$(".object").attrs("level")
...