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Difference between Repository and Service Layer?
... bool Delete(int id);
T Get(int id);
bool SaveChanges();
}
and call Get(id). Repository layer exposes basic CRUD operations.
Service layer exposes business logic, which uses repository. Example service could look like:
public interface IUserService
{
User GetByUserName(string userNa...
What are the rules for the “…” token in the context of variadic templates?
...template parameter pack if it appears on the right side of an expression (call this expression pattern for a moment), or it's a pack argument if it appears on left side of the name:
...thing // pack : appears as template arguments
thing... // unpack : appears when consuming the arguments
The ru...
What does “abstract over” mean?
...the similarities. We say that we abstract over the differences, but this really means we're integrating by the similarities.
For example, consider a program that takes the sum of the numbers 1, 2, and 3:
val sumOfOneTwoThree = 1 + 2 + 3
This program is not very interesting, since it's not very a...
Select distinct values from a table field
...ant any ordering to be applied to a query, not even the default ordering, call order_by() with no parameters.
and distinct() in the note where it discusses issues with using distinct() with ordering.
To query your DB, you just have to call:
models.Shop.objects.order_by().values('city').distinct(...
How do I override __getattr__ in Python without breaking the default behavior?
I want to override the __getattr__ method on a class to do something fancy but I don't want to break the default behavior.
...
How to match a String against string literals in Rust?
...ething else!"),
}
Note that you also have to explicitly handle the catch-all case.
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How to find list intersection?
... looking for a slightly different animal - and you may need to do that manually by sorting each list and merging the results - and keeping dups in the merging.
– javadba
Jan 6 '19 at 18:51
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What is the worst gotcha in C# or .NET? [closed]
...return MyVar; }
}
Blammo. Your app crashes with no stack trace. Happens all the time.
(Notice capital MyVar instead of lowercase myVar in the getter.)
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Only read selected columns
...g","Sep","Oct","Nov","Dec"))
dat <- fread("data.txt", drop = c(8:13))
All result in:
> data
Year Jan Feb Mar Apr May Jun
1 2009 -41 -27 -25 -31 -31 -39
2 2010 -41 -27 -25 -31 -31 -39
3 2011 -21 -27 -2 -6 -10 -32
UPDATE: When you don't want fread to return a data.table, use the data.ta...
Why can I not push_back a unique_ptr into a vector?
...to a local variable. The lifetime of a local variable is managed automatically: local variables are destroyed when the block ends (e.g., when the function returns, in this case). You need to dynamically allocate the object:
std::unique_ptr<int> ptr(new int(1));
...