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Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?
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Generically, a covariant type parameter is one which is allowed to vary down as the class is subtyped (alternatively, vary with subtyping, hence the "co-" prefix). More concretely:
trait List[+A]
List[Int] is a subtype of List[A...
What's the difference between returning void and returning a Task?
... see why returning a Task<MyType> is useful to return data to the caller when the async operation completes, but the functions that I've seen that have a return type of Task never return any data. Why not return void ?
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Force browser to download image files on click
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Not fully supported in all browsers yet but it's a good solution if you don't care about IE or Safari. caniuse.com/#feat=download
– stacigh
Sep 23 '14 at 18:41
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How can I find the number of days between two Date objects in Ruby?
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all of these steered me to the correct result, but I wound up doing
DateTime.now.mjd - DateTime.parse("01-01-1995").mjd
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Is JavaScript's “new” keyword considered harmful?
... to every object I create, I could just write a creation function that manually assigns each method to each new object... Or, I could assign them to the creation function's prototype and use new to stamp out new objects. Not only is this faster (no code needed for each and every method on the protot...
Rule-of-Three becomes Rule-of-Five with C++11?
...(T&& other) as Philipp points out in his answer, if it has dynamically allocated members, or generally stores pointers. Just like you should have a copy-ctor, assignment operator and destructor if the points mentioned before apply.
Thoughts?
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opposite of .gitignore file? [duplicate]
Is it possible to let git ignore all files by default, unless specified in a special file?
2 Answers
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How do CUDA blocks/warps/threads map onto CUDA cores?
I have been using CUDA for a few weeks, but I have some doubts about the allocation of blocks/warps/thread.
I am studying the architecture from a didactic point of view (university project), so reaching peak performance is not my concern.
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How to shrink the .git folder
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you should not delete all changes older than 30 days (i think it's somehow possible exploiting git, but really not recommended).
you can call git gc --aggressive --prune, which will perform garbage collection in your repository and prune old obje...
How to enable MySQL Query Log?
...able, disable and to see the logs on live servers without restarting.
Log all queries in mysql
Here is a summary:
If you don't want or cannot restart the MySQL server you can proceed like this on your running server:
Create your log tables (see answer)
Enable Query logging on the database
(No...