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How can I rename a database column in a Ruby on Rails migration?
...mething else or do nothing
end
end
For Rails 3.1 use:
While, the up and down methods still apply, Rails 3.1 receives a change method that "knows how to migrate your database and reverse it when the migration is rolled back without the need to write a separate down method".
See "Active Record...
windows service vs scheduled task
What are the cons and pros of windows services vs scheduled tasks for running a program repeatedly (e.g. every two minutes)?
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How to create a release signed apk file using Gradle?
...KEY_ALIAS=*****
RELEASE_KEY_PASSWORD=*****
Modify your app/build.gradle, and add this inside the android { code block:
...
signingConfigs {
release {
storeFile file(RELEASE_STORE_FILE)
storePassword RELEASE_STORE_PASSWORD
keyAlias RELEASE_KEY_ALIAS
keyPassword ...
Efficient way to return a std::vector in c++
How much data is copied, when returning a std::vector in a function and how big an optimization will it be to place the std::vector in free-store (on the heap) and return a pointer instead i.e. is:
...
Java 8: performance of Streams vs Collections
... the middle of the list using iterator.
Stop writing benchmarking code by hand, use JMH.
Proper benchmarks:
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@BenchmarkMode(Mode.AverageTime)
@OperationsPerInvocation(StreamVsVanilla.N)
public class StreamVsVanilla {
public static final int N = 10000;
...
Declaring variables inside loops, good practice or bad practice?
...
The compiler knows that the variable scope is limited to inside the loop, and therefore will issue a proper error message if the variable is by mistake referenced elsewhere.
Last but not least, some dedicated optimization can be performed more efficiently by the compiler (most importantly register ...
When should the xlsm or xlsb formats be used?
... (in particular, .xlsx , .xlsm , .xlsb ). I've got no problem to understand the use and purpose of .xlsx format but I am still wondering whether we should use a .xlsm or a .xlsb format when creating a file containing some VBA.
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Bootstrap carousel multiple frames at once
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Updated 2019...
Bootstrap 4
The carousel has changed in 4.x, and the multi-slide animation transitions can be overridden like this...
.carousel-inner .carousel-item-right.active,
.carousel-inner .carousel-item-next {
transform: translateX(33.33%);
}
.carousel-inner .carousel-item-l...
Remove the bottom divider of an android ListView
...
Just add
android:footerDividersEnabled="false"
to your ListView description
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Difference between /res and /assets directories
...le system, but I would like to know, in general, when it's best to use one and the other.
Can anyone help me in knowing the real differences between res and assets?
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