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Hidden features of Scala
... (1, 3.14159, "Hello, world")
The right hand expression creates a Tuple3[Int, Double, String] which can match the pattern (a, b, c).
Most of the time your patterns use extractors that are members of singleton objects. For example, if you write a pattern like
Some(value)
then you're implicitly...
Group by multiple columns in dplyr, using string vector input
...orm(100)
)
# Columns you want to group by
grp_cols <- names(df)[-3]
# Convert character vector to list of symbols
dots <- lapply(grp_cols, as.symbol)
# Perform frequency counts
df %>%
group_by_(.dots=dots) %>%
summarise(n = n())
output:
Source: local data frame [9 x 3]
Grou...
Does Typescript support the ?. operator? (And, what's it called?)
..., including the type conversions such as...
var n: number = +myString; // convert to number
var b: bool = !!myString; // convert to bool
Manual Solution
But back to the question. I have an obtuse example of how you can do a similar thing in JavaScript (and therefore TypeScript) although I'm defi...
Shortcut to create properties in Visual Studio?
...n tab twice. That would generate the field and the full property.
private int myVar;
public int MyProperty
{
get { return myVar;}
set { myVar = value;}
}
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A reference to the dll could not be added
...I used it but it has to do with registering COM servers so certain entry points need to be available. If regsvr32 fails the DLL doesn't provide those entry points and the DLL does not contain a COM component.
You only chance for using the DLL is to import it like any other non-.NET binary, e.g. whe...
How to use an existing database with an Android application [duplicate]
...e static String DB_NAME ="YourDbName"; // Database name
private static int DB_VERSION = 1; // Database version
private final File DB_FILE;
private SQLiteDatabase mDataBase;
private final Context mContext;
public DataBaseHelper(Context context) {
super(context, DB_NAME, n...
How to use MDC with thread pools?
...
Yes, this is a common problem I've run into as well. There are a few workarounds (like manually setting it, as described), but ideally you want a solution that
Sets the MDC consistently;
Avoids tacit bugs where the MDC is incorrect but you don't know it; and
Min...
How do I verify a method was called exactly once with Moq?
...
Imagine we are building a calculator with one method for adding 2 integers. Let's further imagine the requirement is that when the add method is called, it calls the print method once. Here is how we would test this:
public interface IPrinter
{
void Print(int answer);
}
public class C...
Mapping composite keys using EF code first
...
public string SomeId { get; set; }
[Key, Column(Order = 1)]
public int OtherId { get; set; }
}
You can also look at this SO question. If you want official documentation, I would recommend looking at the official EF website. Hope this helps.
EDIT: I just found a blog post from Julie Lerman...
What is the most “pythonic” way to iterate over a list in chunks?
I have a Python script which takes as input a list of integers, which I need to work with four integers at a time. Unfortunately, I don't have control of the input, or I'd have it passed in as a list of four-element tuples. Currently, I'm iterating over it this way:
...