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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 is the proper way to check for existence of variable in an EJS template (using ExpressJS)?
...S 2.3.4 EDIT: using locals in place of this works
– X_Trust
Feb 9 '16 at 21:21
add a comment
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Nokogiri installation fails -libxml2 is missing
I always worked my way around Nokogiri installation issues by following the documentation in the " Installing Nokogiri " tutorial.
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Rails 4: List of available datatypes
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Here are all the Rails 4 (ActiveRecord migration) datatypes:
:binary
:boolean
:date
:datetime
:decimal
:float
:integer
:bigint
:primary_key
:references
:string
:text
:time
:timestamp
Source: http://api.rubyonrails.org/classes/Acti...
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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Tying in to Django Admin's Model History
...ty Alchin's approach has been open sourced and extended in an application called django-simple-history.
– Trey Hunner
Sep 6 '11 at 17:41
5
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Add one row to pandas DataFrame
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Consider adding the index to preallocate memory (see my answer)
– FooBar
Jul 23 '14 at 14:22
34
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Get timezone from DateTime
...mezone information. It may know if it's UTC or local, but not what local really means.
DateTimeOffset is somewhat better - that's basically a UTC time and an offset. However, that's still not really enough to determine the timezone, as many different timezones can have the same offset at any one po...
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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Form inside a form, is that alright? [duplicate]
...HTML5 input element's form attribute. Although we don't nest forms structurally, inputs are evaluated as they are in their own form. In my tests, 3 major browsers support this except IE(IE11). Form nesting limitation was a big obstacle for HTML UI design.
Here is a sample code, when you click Save ...