notation

After a deep dive into an Angular 4.3.* source code I was bumping into ɵ symbol quite often. For example, in async pipe source we see the usage of ɵisPromise(_) and ɵisObservable(_) functions. So now I wonder why Angular team decided to use it? And what does it mean? It seems that Angular devs mark methods/modules with ɵ to emphasize they are some kind of inner entities that should never be imported. But I didn`t find any authoritative proofs. After some deeper research I found another interesting fact: basically ɵ is a letter in several Latin-script alphabets (according to wiki was included

Here is a code snippet from Apple's "Your First iOS Application" document. - (IBAction)changeGreeting:(id)sender { self.userName = textField.text; NSString *nameString = self.userName; if ([nameString length] == 0) { nameString = @"World"; } NSString *greeting = [[NSString alloc] initWithFormat:@"Hello, %@!", nameString]; label.text = greeting; [greeting release]; } I understand that self.username calls the synthesized set method (important since it has a copy flag). Why is textField.text and label.text not self.textField.text and self.label.text. Are the two equivalent? Is the self

I am trying to use an Open Type music font called Bravura Text . I want to use that font in an application that I am currently developing. I did a little research on the features of Bravura Text and the documentation of the font points out, that it is possible to write notes and adjust their vertical position on a staff . There are special characters to raise/lower a notehead on the staff to represent the different tones. I tried to use that features in text applications like Word 2013, Open Office Writer and Libre Office Writer. But I didn't manage to raise/lower the noteheads. All I can see

So, I've just learned that instead of writing things like: [1,2,3,4,5].inject {|x,y| x + y} => 15 I could write [1,2,3,4,5].inject(:+) => 15 I also learned that instead of writing [1,2,3,4,5].select {|x| x.even?} => [2,4] I could write [1,2,3,4,5].select(&:even?) => [2,4] My question is why one (select) uses the & and the other one (inject) doesn't. I'm sure that the : are because even? and + are treated at symbols, but I'd love clarification behind why the & is used in one and why the : are used. Also, I'm aware that I could do these notations on more than just inject and select . Many thanks

Closed . This question needs to be more focused. It is not currently accepting answers. Learn more . Want to improve this question? Update the question so it focuses on one problem only by editing this post . I'm writing an iPhone app where I'd like to display some simple musical notation (just a chord or two). This question is a call for suggestions on the quickest way to go about it. For instance: Is there any iphone OR objective-C libraries for doing this that I'm missing? Are there any examples of open-source objective-C software in the wild I could look at? It wouldn't have to be iPhone

I got this plot using the code below In my plot, I want the NO3 to have negative sign"-" as superscript like below In the label of x axis, I couldn't use negative sign only as a superscript to NO3 so I had to use -1 as shown below x <- seq(0,2*pi,0.1) y <- sin(x) df <- data.frame(x, y) ggplot(df, aes(x=x, y=y))+ geom_point(size=4)+ labs(x=expression(Production~rate~" "~mu~moles~NO[3]^{-1}-N~Kg^{-1}), y=expression(Concentration~mg~L^{-1})) Any suggestions on how to change the label to have a negative sign only without 1? Try quoting the minus sign after the superscript operator: ggplot(df, aes