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Rails migration for change column
...l situations where the existing data, let's say a String can be implicitly converted into the new datatype, let's say Date.
In this situation, it's helpful to know you can create migrations with data conversions. Personally, I like putting these in my model file, and then removing them after all d...
Why use apparently meaningless do-while and if-else statements in macros?
...e.
if (corge)
BAR(corge);
else
gralt();
The above code would expand into
if (corge)
f(corge); g(corge);
else
gralt();
which is syntactically incorrect, as the else is no longer associated with the if. It doesn't help to wrap things in curly braces within the macro, because a semicolon...
How to implement static class member functions in *.cpp file?
...
It is.
test.hpp:
class A {
public:
static int a(int i);
};
test.cpp:
#include <iostream>
#include "test.hpp"
int A::a(int i) {
return i + 2;
}
using namespace std;
int main() {
cout << A::a(4) << endl;
}
They're not always inline, no...
Resize image proportionally with MaxHeight and MaxWidth constraints
...g", ImageFormat.Png);
}
}
public static Image ScaleImage(Image image, int maxWidth, int maxHeight)
{
var ratioX = (double)maxWidth / image.Width;
var ratioY = (double)maxHeight / image.Height;
var ratio = Math.Min(ratioX, ratioY);
var newWidth = (int)(image.Width * ratio);
...
What's the syntax for mod in java
... modulo operator, which has slightly different semantics, for non-negative integers, you can use the remainder operator %. For your exact example:
if ((a % 2) == 0)
{
isEven = true;
}
else
{
isEven = false;
}
This can be simplified to a one-liner:
isEven = (a % 2) == 0;
...
:: (double colon) operator in Java 8
...
Usually, one would call the reduce method using Math.max(int, int) as follows:
reduce(new IntBinaryOperator() {
int applyAsInt(int left, int right) {
return Math.max(left, right);
}
});
That requires a lot of syntax for just calling Math.max. That's where lambda ...
Custom ImageView with drop shadow
...This is taken from Romain Guy's presentation at Devoxx, pdf found here.
Paint mShadow = new Paint();
// radius=10, y-offset=2, color=black
mShadow.setShadowLayer(10.0f, 0.0f, 2.0f, 0xFF000000);
// in onDraw(Canvas)
canvas.drawBitmap(bitmap, 0.0f, 0.0f, mShadow);
Hope this helps.
NOTES
Do...
What does Expression.Quote() do that Expression.Constant() can’t already do?
...xtremely confusing and bug prone.
Long answer:
Consider the following:
(int s)=>(int t)=>s+t
The outer lambda is a factory for adders that are bound to the outer lambda's parameter.
Now, suppose we wish to represent this as an expression tree that will later be compiled and executed. Wh...
How to use C++ in Go
... linking a small test C++ class with Go
If you wrap you C++ code with a C interface you should be able to call your library with cgo (see the example of gmp in $GOROOT/misc/cgo/gmp).
I'm not sure if the idea of a class in C++ is really expressible in Go, as it doesn't have inheritance.
Here's an...
Are static fields inherited?
...
3 in all cases, since the static int total inherited by SomeDerivedClass is exactly the one in SomeClass, not a distinct variable.
Edit: actually 4 in all cases, as @ejames spotted and pointed out in his answer, which see.
Edit: the code in the second ques...