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Why Func instead of Predicate?
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Well, actually you have to place that in the context of the guideline, which is about writing a LINQ provider. So yeah, for LINQ operators, the guideline is to use Func<> and Expression<> as parameters for the extension met...
When to use the different log levels
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I generally subscribe to the following convention:
Trace - Only when I would be "tracing" the code and trying to find one part of a function specifically.
Debug - Information that is diagnostically helpful to people more than just...
How can I provide multiple conditions for data trigger in WPF?
...D are false, and set the default to true.
– WeSam Abdallah
Oct 28 '14 at 15:47
3
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Using Java 8's Optional with Stream::flatMap
...latMap(Optional::stream)
.findFirst();
Java 8
Yes, this was a small hole in the API, in that it's somewhat inconvenient to turn an Optional<T> into a zero-or-one length Stream<T>. You could do this:
Optional<Other> result =
things.stream()
.map(this::resolv...
Why use symbols as hash keys in Ruby?
...saves memory, because they are only stored once.
Symbols in Ruby are basically "immutable strings" .. that means that they can not be changed, and it implies that the same symbol when referenced many times throughout your source code, is always stored as the same entity, e.g. has the same object id...
What's the difference between Ruby's dup and clone methods?
..., name: "Favorites">
clone creates a new object with the same id, so all the changes made to that new object will overwrite the original record if hitting .save
category2 = category.clone
#=> #<Category id: 1, name: "Favorites">
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Running a Haskell program on the Android OS
...ndroid NDK which comes with a GCC port for ARM architectures. JHC can trivially do this with a very small inf style file which describes the platform (word size, c-compiler, etc) I've done this with the Wii homebrew dev kit and it was quite easy. However jhc still has some stability issues with comp...
Read an Excel file directly from a R script
...e gdata package works most of the time (although you need to have Perl installed on your system -- usually already true on MacOS and Linux, but takes an extra step on Windows, i.e. see http://strawberryperl.com/). There are various caveats, and alternatives, listed on the R wiki page.
The only reas...
How can I add to List
...t<? extends T> because you can't guarantee what kind of List it is really pointing to, so you can't guarantee that the object is allowed in that List. The only "guarantee" is that you can only read from it and you'll get a T or subclass of T.
The reverse logic applies to super, e.g. List<?...
Most efficient way of making an if-elif-elif-else statement when the else is done the most?
...doThisMostOfTheTime)()
...looks like it ought to be faster, but it's actually slower than the if ... elif ... else construct, because it has to call a function, which can be a significant performance overhead in a tight loop.
Consider these examples...
1.py
something = 'something'
for i in xra...