tilde

What does a tilde in angle brackets mean when creating a Java generic class?

由 余生长醉 提交于 2019-11-26 15:29:03
问题 I was reading through some JMockit examples and found this code: final List<OrderItem> actualItems = new ArrayList<~>(); What does the tilde in the generic identifier mean? I know it's the unary bitwise NOT operator, but I don't see an operand here. Also, I tried compiling it and got an error. Am I just missing something? 回答1: It is just a shorthand for "same as in declaration". Some IDEs, e.g. IntelliJ use this too. The files on disk do not have this notation, which is only a compaction in

In R formulas, why do I have to use the I() function on power terms, like y ~ I(x^3)

由 若如初见. 提交于 2019-11-26 15:24:10
问题 I'm trying to get my head around the use of the tilde operator, and associated functions. My 1st question is why does I() need to be used to specify arithmetic operators? For example, these 2 plots generate different results (the former having a straight line, and the latter the expected curve) x <- c(1:100) y <- seq(0.1,10,0.1) plot(y~x^3) plot(y~I(x^3)) further, both of the following plots also generate the expected result plot(x^3, y) plot(I(x^3), y) My second question is, perhaps the

What is meaning of first tilde in purrr::map

由 时光总嘲笑我的痴心妄想 提交于 2019-11-26 12:27:48
问题 I was looking at this example that uses map . Here it is: mtcars %>% split(.$cyl) %>% # from base R map(~ lm(mpg ~ wt, data = .)) What is the meaning of the first tilde in map(~ lm... ? That is, how does R interpret the first tilde? (I understand that the second tilde indicates a function...) . Another way of asking is, why doesn\'t the following work? mtcars %>% split(.$cyl) %>% # from base R map(lm(mpg ~ wt, data = .)) 回答1: As per the map help documentation, map needs a function but it also

What does the tilde before a function name mean in C#?

由 好久不见. 提交于 2019-11-26 11:14:32
I am looking at some code and it has this statement: ~ConnectionManager() { Dispose(false); } The class implements the IDisposable interface, but I do not know if that is part of that the tilde(~) is used for. Patrick Desjardins ~ is the destructor Destructors are invoked automatically, and cannot be invoked explicitly. Destructors cannot be overloaded. Thus, a class can have, at most, one destructor. Destructors are not inherited. Thus, a class has no destructors other than the one, which may be declared in it. Destructors cannot be used with structs. They are only used with classes. An

Difference between ./ and ~/

由 Deadly 提交于 2019-11-26 08:35:55
问题 When creating filepaths and URLs, I noticed that many times the path starts with ./ or ~/ . What is the difference between filepaths that start with ./ and ~/ ? What do each of them mean? 回答1: ./ means "starting from the current directory". . refers to the current working directory, so something like ./foo.bar would be looking for a file called foo.bar in the current directory. (As a side note, .. means refers to the parent directory of the current directory. So ../foo.bar would be looking

What does the tilde before a function name mean in C#?

由 泄露秘密 提交于 2019-11-26 02:19:11
问题 I am looking at some code and it has this statement: ~ConnectionManager() { Dispose(false); } The class implements the IDisposable interface, but I do not know if that is part of that the tilde(~) is used for. 回答1: ~ is the destructor Destructors are invoked automatically, and cannot be invoked explicitly. Destructors cannot be overloaded. Thus, a class can have, at most, one destructor. Destructors are not inherited. Thus, a class has no destructors other than the one, which may be declared
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