colon-equals

In the Go web server example here: http://golang.org/doc/effective_go.html#web_server The following line of code works var addr = flag.String("addr", ":1718", "http service address") but changing it to addr := flag.String("addr", ":1718", "http service address") is a compilation error. Why? Does it have anything to do with the face that the return type of the function is *string instead of string ? What difference does that make? UPDATE : Thanks for pointing out that := is not allowed at the top level. Any idea why this inconsistency is in the spec? I don't see any reason for the behaviour to

Currently, I am learning some FPGA design techniques using VHDL, my problem is whether we can use := and <= interchangeably in VHDL or not, though I've seen the use of := in constants declarations and <= in assignments? Thanks in advance! The rules are a little more complex than this, but basically: you use <= to do signal assignment, which takes effect on the next delta cycle. You use := to do variable assignment, which takes place immediately. So if you have a signal, you always use <= . If you have a variable, you always use := . Some places where this is not quite that case that you will

While reading http://ggvis.rstudio.com/interactivity.html , I noticed the code has := sprinkled in it. I assume that is a new way of providing arguments to a function? What is it exactly? mtcars %>% ggvis(~wt, ~mpg, size := input_slider(10, 1000)) %>% layer_points(fill := "red") %>% layer_points(stroke := "black", fill := NA) In this case, := is simply ggvis' syntax for assigning fixed values; in contrast, = would here be used to assign a variable value. As you might have noticed in your code example, on the right hand side, there are only such values as "red" or NA, therefore := is the right

What is the difference between = and := in Scala? I have googled extensively for "scala colon-equals", but was unable to find anything definitive. Owen = in scala is the actual assignment operator -- it does a handful of specific things that for the most part you don't have control over, such as Giving a val or var a value when it's created Changing the value of a var Changing the value of a field on a class Making a type alias Probably others := is not a built-in operator -- anyone can overload it and define it to mean whatever they like. The reason people like to use := is because it looks

By digging into R source code (file R-3.2.2/src/main/gram.y lines 2836 to 2852) I found that the R parser/tokenizer considers that := is a LEFT_ASSIGNMENT token. But when trying to use it as an assignment operator in R.3.2.2 , I have an error (impossible to find function for := ...) but as you can see R considers it as an assignment like <- : > myVar := 42 Erreur : impossible de trouver la fonction ":=" > := Erreur : unexpected assignment in ":=" > <- Erreur : unexpected assignment in "<-" Is it a bug, or does the token := need to be removed from the tokenizer source code? Is there a past

If foud this code: ActiveCell.Offset(-5, -1).Range("A1:E1").Cut Destination:=ActiveCell.Range( _ "A1:E1") I can't find any reference about ":=". What does it mean? := is used with named arguments. In this case, Destination is the name of an argument to the Cut method, and the other side is its value. See https://docs.microsoft.com/en-us/office/vba/language/concepts/getting-started/understanding-named-arguments-and-optional-arguments for an example. 来源： https://stackoverflow.com/questions/12972637/what-does-mean-the-colon-with-equal-sign