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How does the const constructor actually work?

...a nice performance win for Flutter widgets according to medium.com/@mehmetf_71205/inheriting-widgets-b7ac56dbbeb1 "Use const to build your widgets Without const, selective rebuilding of the sub-tree does not happen. Flutter creates a new instance of each widget in the sub-tree and calls build() was...
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Java Error opening registry key

...eleting the Oracle Folder in my ProgramData – Alyosha_Karamazov Jul 10 '19 at 20:34 add a comment  |  ...
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A Regex that will never be matched by anything

...e of $a. It's Perl equivalent $(?:a) is also very slow perl -Mre=debug -e'$_=a x 50; /$(?:a)/'. – Brad Gilbert Apr 6 '13 at 14:56 ...
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“Unknown class in Interface Builder file” error at runtime

...it, and prints the warning. By default, Objective-C targets will have -all_load -ObjC flags set by default, which will keep all of the symbols. But I had started with a C++ target, and didn't have that. Nevertheless, I found a way around this, which keeps the linker aggressive. The hack I was or...
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UITapGestureRecognizer - single tap and double tap

...UITapGestureRecognizer(target: self, action:#selector(self.singleTapAction(_:))) singleTap.numberOfTapsRequired = 1 view.addGestureRecognizer(singleTap) let doubleTap = UITapGestureRecognizer(target: self, action:#selector(self.doubleTapAction(_:))) doubleTap.numberOfTapsRequired = 2 view.addGestur...
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Why are Subjects not recommended in .NET Reactive Extensions?

...c class MessageListener { private readonly IObservable<IMessage> _messages; private readonly IScheduler _scheduler; public MessageListener() { _scheduler = new EventLoopScheduler(); var messages = ListenToMessages() .Subscri...
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Table name as variable

...or dynamic queries you should generate the full SQL dynamically, and use sp_executesql to execute it. Here is an example of a script used to compare data between the same tables of different databases: static query: SELECT * FROM [DB_ONE].[dbo].[ACTY] EXCEPT SELECT * FROM [DB_TWO].[dbo].[ACTY] ...
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How can I format my grep output to show line numbers at the end of the line, and also the hit count?

... or in perl (for completeness...): perl -npe 'chomp; /null/ and print "$_ - Line number : $.\n" and $i++;$_="";END{print "Total null count : $i\n"}' share | improve this answer | ...
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What does ':' (colon) do in JavaScript?

... is a float. Pretty sur that's what that means. – Sal_Vader_808 May 14 '17 at 11:08 add a comment  |  ...
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Scala: join an iterable of strings

...,"): String = list match { case head :: tail => tail.foldLeft(head)(_ + delim + _) case Nil => "" } – Davos Jul 11 '17 at 14:37 2 ...