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When should I use a struct instead of a class?
...
It logically represents a single value, similar to primitive types
(integer, double, and so on).
It has an instance size smaller than 16 bytes.
It is immutable.
It will not have to be boxed frequently.
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What is the difference between instanceof and Class.isAssignableFrom(…)?
...pes. isAssignableFrom() can be used with any class objects:
a instanceof int // syntax error
3 instanceof Foo // syntax error
int.class.isAssignableFrom(int.class) // true
See http://java.sun.com/javase/6/docs/api/java/lang/Class.html#isAssignableFrom(java.lang.Class).
...
Unique combination of all elements from two (or more) vectors
...s better than the classic expand.grid function because (1) strings are not converted into factors and (2) the sorting is more intuitive:
library(tidyr)
a <- c("ABC", "DEF", "GHI")
b <- c("2012-05-01", "2012-05-02", "2012-05-03", "2012-05-04", "2012-05-05")
crossing(a, b)
# A tibble: 15 x 2...
What is the combinatory logic equivalent of intuitionistic type theory?
...tution), it'll be handy to represent intermediate stages in the process of converting terms with binding to their combinatory form.
Here's normalization:
norm :: Unty a -> Unty a
norm (f :. a) = norm f $. a
norm c = c
($.) :: Unty a -> Unty a -> Unty a -- requires first a...
Is it possible to figure out the parameter type and return type of a lambda?
...aits<ReturnType(ClassType::*)(Args...) const>
// we specialize for pointers to member function
{
enum { arity = sizeof...(Args) };
// arity is the number of arguments.
typedef ReturnType result_type;
template <size_t i>
struct arg
{
typedef typename std:...
Random row from Linq to Sql
...m row in ctx.Customers
where row.IsActive
select row;
int count = qry.Count(); // 1st round-trip
int index = new Random().Next(count);
Customer cust = qry.Skip(index).FirstOrDefault(); // 2nd round-trip
...
Efficient way to remove ALL whitespace from String?
...WhiteSpace1(string input, string expected)
{
string s = null;
for (int i = 0; i < 1000000; i++)
{
s = input.RemoveWhitespace();
}
Assert.AreEqual(expected, s);
}
[Test]
[TestCase("123 123 1adc \n 222", "1231231adc222")]
public void RemoveWhiteSpace2(string input, stri...
How to create a release signed apk file using Gradle?
...he original/default as I use above. They then go on telling you you should convert to the new open PKCS12 format. However, it seem that the Android development tools are not quite ready for this yet, because if you do, you will get the following weird errors:
com.android.ide.common.signing.Keyto...
Programmatically relaunch/recreate an activity?
...a recreate() method to activities.
I've done that by simply reusing the intent that started the activity. Define an intent starterIntent in your class and assign it in onCreate() using starterIntent = getIntent();. Then when you want to restart the activity, call finish(); startActivity(starterIn...
C# elegant way to check if a property's property is null
... you can use the Null Conditional Operator. So the original test will be:
int? value = objectA?.PropertyA?.PropertyB?.PropertyC;
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