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What is an example of the Liskov Substitution Principle?
...
A great example illustrating LSP (given by Uncle Bob in a podcast I heard recently) was how sometimes something that sounds right in natural language doesn't quite work in code.
In mathematics, a Square is a Rectangle. Indeed it is a specialization of a rectangle. The "is a" makes you...
Using the Swift if let with logical AND operator &&
...n("do stuff")
}
This uses the where clause.
Another example, this time casting AnyObject to Int, unwrapping the optional, and checking that the unwrapped optional meets the condition:
if let w = width as? Int where w < 500
{
println("success!")
}
For those now using Swift 3, "where" ha...
Generating a UUID in Postgres for Insert statement?
...afichuk @Karsten and @autronix
Also, in modern Postgres, you can simply cast:
SELECT md5(random()::text || clock_timestamp()::text)::uuid
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Measuring execution time of a function in C++
...::high_resolution_clock::now();
auto duration = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ).count();
std::cout << duration;
return 0;
}
This will measure the duration of the function.
NOTE: You will not always get the same timing for a function. This...
Convert a float64 to an int in Go
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Such casts have a problem in Go that can be unexpected (at least if you come from Java): "In all non-constant conversions involving floating-point or complex values, if the result type cannot represent the value the conversion suc...
Pan & Zoom Image
...he ScaleTransform in a similar manner you get TranslateTransform. That is, Cast it to a TransformGroup then select and cast the appropriate Child. 2) If your movement is Jittery remember that you can't use the image to get your mouse position (since its dynamic), you have to use something static. In...
T-SQL datetime rounded to nearest minute and nearest hours with using functions
...en the datetime in question and a fixed point in time (0, which implicitly casts to 1900-01-01 00:00:00.000):
declare @days int
set @days = datediff(day, 0, @dt)
and then add that number of days to the fixed point in time, which gives you the original date with the time set to 00:00:00.000:
sele...
Safe (bounds-checked) array lookup in Swift, through optional bindings?
..., to clarify the situation: b contains a value and the value is nil. If we casted automatically to Int?, we would loose the information, if we got a hit or a miss in the array, which might be necessary in some circumstances. I would rather debate, if Swift could get rid of automatically casting valu...
MIN and MAX in C
... macro from doing such potentially dangerous type promotions, a final type cast to the intended type was used.
Rationale
We want both parameters to the macro to be of the same type. If one of them is of a different type, the macro is no longer type safe, because an operator like ?: will yield impl...
How to handle click event in Button Column in Datagridview?
...ll have to check for that below.
Dos:
So here's what you should do:
First, cast the sender to type DataGridView to expose it's internal properties at design time. You can modify the type on the parameter, but that can sometimes make adding or removing handlers tricky.
Next, to see if a button was c...