Ah found it...functions that accept variable length arguments are called **Variadic Functions**. Example:


    package main
    
    import &quot;fmt&quot;
    
    func MyPrint(format string, args ...interface{}) {
      fmt.Printf(&quot;[MY PREFIX] &quot; + format, args...)
    }
    
    func main() {
     MyPrint(&quot;yay %d %d\n&quot;,123,234);
     MyPrint(&quot;yay %d\n &quot;,123);
     MyPrint(&quot;yay %d\n&quot;);
    }

I&#39;m trying to implement long polling for the first time, and I&#39;m using XMLHttpRequest objects to do it. So far, I&#39;ve been successful at getting events in Firefox and Internet Explorer 11, but Chrome strangely is the odd one out this time.

I can load one page and it runs just fine. It makes the request right away and starts processing and displaying events. If I open the page in a second tab, one of the pages starts seeing delays in receiving events. In the dev tools window, I see multiple requests with this kind of timing:

  ![screenshot](http://i.stack.imgur.com/qFDtX.png)

&quot;Stalled&quot; will range up to 20 seconds. It won&#39;t happen on every request, but will usually happen on several requests in a row, and in one tab.

At first I thought this was an issue with my server, but then I opened two IE tabs and two Firefox tabs, and they all connect and receive the same events without stalling. Only Chrome is having this kind of trouble.

I figure this is likely an issue with the way in which I&#39;m making or serving up the request. For reference, the request headers look like this:

    Connection: keep-alive
    Last-Event-Id: 530
    User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36
    Accept: */*
    DNT: 1
    Accept-Encoding: gzip, deflate, sdch
    Accept-Language: en-US,en;q=0.8

The response looks like this:

    HTTP/1.1 200 OK
    Cache-Control: no-cache
    Transfer-Encoding: chunked
    Content-Type: text/event-stream
    Expires: Tue, 16 Dec 2014 21:00:40 GMT
    Server: Microsoft-HTTPAPI/2.0
    Date: Tue, 16 Dec 2014 21:00:40 GMT
    Connection: close

In spite of the headers involved, I&#39;m not using the browser&#39;s native EventSource, but rather a polyfill that lets me set additional headers. The polyfill is using XMLHttpRequest under the covers, but it seems to me that no matter how the request is being made, it shouldn&#39;t stall for 20 seconds.

What might be causing Chrome to stall like this?

**Edit:** Chrome&#39;s chrome://net-internals/#events page shows that there&#39;s a timeout error involved:

    t=33627 [st=    5]      HTTP_CACHE_ADD_TO_ENTRY  [dt=20001]
                    --&gt; net_error = -409 (ERR_CACHE_LOCK_TIMEOUT)

The error message refers to a patch added to Chrome six months ago (https://codereview.chromium.org/345643003), which implements a 20-second timeout when the same resource is requested multiple times. In fact, one of the bugs the patch tries to fix ([bug number 46104](https://code.google.com/p/chromium/issues/detail?id=46104)) refers to a similar situation, and the patch is meant to *reduce* the time spent waiting.

It&#39;s possible the answer (or workaround) here is just to make the requests look different, although perhaps Chrome could respect the &quot;no-cache&quot; header I&#39;m setting.



Chrome stalls when making multiple requests to same resource?

All C compilers I&#39;ve tried won&#39;t detect uninitialized variables in the code snippet below. Yet the case is obvious here.

Don&#39;t bother about the functionality of this snippet. It&#39;s not real code, and I stripped it down for the investigation of this issue.

    BOOL NearEqual (int tauxprecis, int max, int value)
    {
      int tauxtrouve;      // Not initialized at this point
      int totaldiff;       // Not initialized at this point

      for (int i = 0; i &lt; max; i++)
      {
        if (2 &lt; totaldiff)  // At this point totaldiff is not initialized
        {
          totaldiff = 2;
          tauxtrouve = value;  // Commenting this line out will produce warning
        }
      }

      return tauxtrouve == tauxprecis ;  // At this point tauxtrouve is potentially
                                         // not initialized.
    }

On the other hand, if I comment out `tauxtrouve = value ;`, I get the `&quot;local variable &#39;tauxtrouve&#39; used without having been initialized&quot;` warning.

I tried these compilers:

 - [GCC][1] 4.9.2 with -Wall -WExtra
 - Microsoft Visual C++ 2013 with all warnings enabled

  [1]: http://en.wikipedia.org/wiki/GNU_Compiler_Collection


Compiler not detecting obviously uninitialized variable

How to pass variable length arguments in `Go`? for example, I want to call

    func MyPrint(format string, args ...interface{}) {
      fmt.Printf(&quot;[MY PREFIX] &quot; + format, ???)
    }

    // to be called as: MyPrint(&quot;yay %d&quot;, 213) 
    //              or  MyPrint(&quot;yay&quot;)
    //              or  MyPrint(&quot;yay %d %d&quot;,123,234)

How to pass variable length arguments as arguments on another function in Golang?

How to pass variable length arguments in <code>Go</code>? for example, I want to call
<pre><code class="hljs language-perl">func MyPrint(format string, args ...interface{}) {
 fmt.Printf("[MY PREFIX] " + format, ???)
}

// to be called as: MyPrint("yay %d", 213) 
// or MyPrint("yay")
// or MyPrint("yay %d %d",123,234)
</code></pre>

How do I return 3 separate data values of the same type(Int) from a function in swift?

I&#39;m attempting to return the time of day, I need to return the Hour, Minute and Second as separate integers, but all in one go from the same function, is this possible?

I think I just don&#39;t understand the syntax for returning multiple values. This is the code I&#39;m using, I&#39;m having trouble with the last(return) line.

Any help would be greatly appreciated!

    func getTime() -&gt; Int
    {
        let date = NSDate()
        let calendar = NSCalendar.currentCalendar()
        let components = calendar.components(.CalendarUnitHour | .CalendarUnitMinute | .CalendarUnitSecond, fromDate: date)
        let hour = components.hour
        let minute = components.minute
        let second = components.second
        let times:String = (&quot;\(hour):\(minute):\(second)&quot;)
        return hour, minute, second
    }

Return multiple values from a function in swift

I&#39;m afraid that this is somewhat a silly question.

Is there anybody can tell me why there is no `BooleanConsumer` opposite to [`BooleanSupplier`](https://docs.oracle.com/javase/8/docs/api/java/util/function/BooleanSupplier.html)?

Is there any reason other than &quot;because simply there isn&#39;t&quot;?

Should I create my own one? Or am I missing something else?

&lt;!-- language: java --&gt;

    public interface BooleanConsumer {
    
        void accept(boolean value);
    
        default BooleanConsumer andThen(final BooleanConsumer after) {
            return v -&gt; {
                accept(v);
                after.accept(v);
            }
        }
    }

### Update

Where to use? I&#39;m writing a library that uses much of consumers and suppliers. I successfully wrote a line with `LongConsumer` and I encountered a situation that expecting a consumer accepting a boolean value which is from a method result. Say `Files.deleteIfExist`? 

Why there is no BooleanConsumer in Java 8?

It is very unclear for me in which case I would want to use a value receiver instead of always using a pointer receiver.   

To recap from the docs:

    type T struct {
    	a int
    }
    func (tv  T) Mv(a int) int         { return 0 }  // value receiver
    func (tp *T) Mp(f float32) float32 { return 1 }  // pointer receiver

The **docs** also say &quot;For types such as basic types, slices, and small structs, a value receiver is very cheap so unless the semantics of the method requires a pointer, a value receiver is efficient and clear.&quot;

**First point** they docs say a value receiver is &quot;very cheap&quot;, but the question is whether it is cheaper than a pointer receiver. So I made a small benchmark [(code on gist)][1] which showed me, that pointer receiver is faster even for a struct that has only one string field. These are the results:

    // Struct one empty string property
    BenchmarkChangePointerReceiver  2000000000               0.36 ns/op
    BenchmarkChangeItValueReceiver  500000000                3.62 ns/op


    // Struct one zero int property
    BenchmarkChangePointerReceiver  2000000000               0.36 ns/op
    BenchmarkChangeItValueReceiver  2000000000               0.36 ns/op

_(Edit: Please note that second point became invalid in newer go versions, see comments.)_

**Second point** the docs say that a value receiver it is &quot;efficient and clear&quot; which is more a matter of taste, isn&#39;t it? Personally I prefer consistency by using the same thing everywhere. Efficiency in what sense? Performance wise it seems pointer are almost always more efficient. Few test-runs with one int property showed minimal advantage of Value receiver (range of 0.01-0.1 ns/op)

Can someone tell me a case where a value receiver clearly makes more sense than a pointer receiver? Or am I doing something wrong in the benchmark? Did I overlook other factors?


  [1]: https://gist.github.com/chrisport/f28674850ffc3d9238f8

Value receiver vs. pointer receiver

I ask because my compiler seems to think so, even though I don’t.

`echo &#39;int main;&#39; | cc -x c - -Wall`  
`echo &#39;int main;&#39; | c++ -x c++ - -Wall`

Clang issues no warning or error with this, and gcc issues only the meek warning: `&#39;main&#39; is usually a function [-Wmain]`, but only when compiled as C. Specifying a `-std=` doesn’t seem to matter.

Otherwise, it compiles and links fine. But on execution, it terminates immediately with `SIGBUS` (for me). 

Reading through the (excellent) answers at https://stackoverflow.com/questions/204476/what-should-main-return-in-c-and-c and a quick grep through the language specs, it would certainly **seem** to me that a main _function_ is required. But the verbiage from gcc’s `-Wmain` (‘main’ is **_usually_** a function) (and the dearth of errors here) seems to possibly suggest otherwise.

But why? Is there some strange edge-case or “historical” use for this? Anyone know what gives?

My point, I suppose, is that I really think this should be an **error** in a hosted environment, eh?

Is ‘int main;’ a valid C/C++ program?

I am interested in what is the &quot;correct&quot; way to write functions with optional arguments in R.
Over time, I stumbled upon a few pieces of code that take a different route here, and I couldn&#39;t find a proper (official) position on this topic.

Up until now, I have written optional arguments like this:

    fooBar &lt;- function(x,y=NULL){
      if(!is.null(y)) x &lt;- x+y
      return(x)
    }
    fooBar(3) # 3
    fooBar(3,1.5) # 4.5

The function simply returns its argument if only `x` is supplied. It uses a default `NULL` value for the second argument and if that argument happens to be not `NULL`, then the function adds the two numbers.

Alternatively, one could write the function like this (where the second argument needs to be specified by name, but one could also `unlist(z)` or define `z &lt;- sum(...)` instead):

    fooBar &lt;- function(x,...){
      z &lt;- list(...)
      if(!is.null(z$y)) x &lt;- x+z$y
      return(x)
    }
    fooBar(3) # 3
    fooBar(3,y=1.5) # 4.5

Personally I prefer the first version. However, I can see good and bad with both. The first version is a little less prone to error, but the second one could be used to incorporate an arbitrary number of optionals.

Is there a &quot;correct&quot; way to specify optional arguments in R? So far, I have settled on the first approach, but both can occasionally feel a bit &quot;hacky&quot;.

&quot;Correct&quot; way to specifiy optional arguments in R functions

What&#39;s the correct way to get all client&#39;s IP Addresses from `http.Request`? In `PHP` there are a lot of [variables][1] that I should check. Is it the same on Go? 

One that I found is:

    req.RemoteAddr

And is the request case sensitive? for example `x-forwarded-for` is the same as `X-Forwarded-For` and `X-FORWARDED-FOR`? (from `req.Header.Get(&quot;X-FORWARDED-FOR&quot;)`)

  [1]: https://stackoverflow.com/questions/15699101/get-the-client-ip-address-using-php

Correct way of getting Client&#39;s IP Addresses from http.Request

I&#39;m new to Go and I&#39;m trying to set up a Go project with minimal documentation: https://github.com/alphagov/metadata-api

I&#39;ve cloned it, but when I try `go build` I get the following warnings: 

    main.go:8:2: cannot find package &quot;github.com/Sirupsen/logrus&quot; in any of:
    	/usr/local/Cellar/go/1.3.3/libexec/src/pkg/github.com/Sirupsen/logrus (from $GOROOT)
    	/Users/me/go/src/github.com/Sirupsen/logrus (from $GOPATH)
    main.go:14:2: cannot find package &quot;github.com/alphagov/metadata-api/content_api&quot; in any of:
    	/usr/local/Cellar/go/1.3.3/libexec/src/pkg/github.com/alphagov/metadata-api/content_api (from $GOROOT)
    	/Users/me/go/src/github.com/alphagov/metadata-api/content_api (from $GOPATH)

I&#39;m guessing this is because I haven&#39;t installed the Go equivalent of requirements? 

My `GOPATH` is set:

    metadata-api$ echo $GOPATH
    /Users/me/go

And the Go executable is in 

    metadata-ape$ echo $PATH
    ....:/Users/me/go/bin

What do I need to do to help Go find these packages?

How do I install requirements in Go? &quot;cannot find package&quot;

We can easily do that with maps:

    item, ok := myMap[&quot;index&quot;]

But not with slices:
    
    item, ok := mySlice[3] // panic!

Surprised this wasn&#39;t asked before. Maybe I&#39;m on the wrong mental model with Go slices?

How to check if a slice has a given index in Go?

I am trying to generate a map and then convert that to a yaml file like this:

    uid :
          kasi:
            cn: Chaithra
            street: fkmp
          nandan:
            cn: Chaithra
            street: fkmp
          remya:
            cn: Chaithra
            street: fkmp

I think I am missing something important while creating the map. My code is below.

    package main
    
    import (
    	&quot;fmt&quot;
    	&quot;gopkg.in/yaml.v2&quot;
    )
    
    type T struct {
    	cn     string
    	street string
    }
    
    func main() {
    	names := []string{&quot;kasi&quot;, &quot;remya&quot;, &quot;nandan&quot;}
    
    	m := make(map[string]map[string]T, len(names))
    	for _, name := range names {
    
    		//t := T{cn: &quot;Chaithra&quot;, street: &quot;fkmp&quot;}
    
    		m[&quot;uid&quot;][name] = T{cn: &quot;Chaithra&quot;, street: &quot;fkmp&quot;}
    
    	}
    	fmt.Println(m)
    
    	y, _ := yaml.Marshal(&amp;m)
    
    	fmt.Println(string(y))
    	//fmt.Println(m, names)
    }

It is giving the following error:

    panic: runtime error: assignment to entry in nil map



Runtime error: assignment to entry in nil map

Using `struct` and a function that is supposed to print out the struct&#39;s elements, I have written this simple program:

    package main
    
    import &quot;fmt&quot;
    
    type Salutation struct {
    	name     string
    	greeting string
    }
    
    func Greet(salutation Salutation) {
    	fmt.Println(salutation.name)
    	fmt.Println(salutation.greeting)
    }
    
    func main() {
    	var s = Salutation
    	s.name = &quot;Alex&quot;
    	s.greeting = &quot;Hi&quot;
    	Greet(s)
    }

When I run it I get the error `go:16: type Salutation is not an expression`. What goes wrong here?

Interestingly enough, when I change the definition of `s` to `var s = Salutation {&quot;Alex&quot;, &quot;Hi&quot;}` it works just fine. But they are basically different syntactic ways to define the same entity. That&#39;s why I don&#39;t understand the source of the error. 
 

Error: struct Type is not an expression

How can I create a function with a variable number of arguments in Rust?

Like this Java code:

    void foo(String... args) {
        for (String arg : args) {
            System.out.println(arg);
        }
    }

How can I create a function with a variable number of arguments?

Consider the code below:

    private def test(some:String*){

    }

    private def call () {
      val some = Array(&quot;asd&quot;, &quot;zxc&quot;)
      test(some)
    }

It prints `expect String, found Array[String]` Why? Are Scala varargs not arrays?

**Note**

I found several questions on Stack Overflow about Scala varargs, but all of them are about calling Java varargs methods or about converting Scala lists to arrays.


How to pass Scala array into Scala vararg method?

I&#39;m a little confused about Java&#39;s *varargs* methods:

    public static int sum(int ...a) {
        return 0;
    }
    
    public static double sum(double ...a) {
        return 0.0;
    }

When I tried to invoke `sum()` without passing any argument, then the `int` version of method was invoked. I don&#39;t understand why; normally the compiler must raise an error.

By contrast, the following piece of code generates a compiler error when I try to invoke `sum` without any argument:

    public static int sum(int ...a) {
        return 0;
    }
    
    public static boolean sum(boolean ...a) {
        return true;
    }

Varargs Java Ambiguous Call

I am confused about the spread syntax and rest parameter in ES2015. Can anybody explain the difference between them with proper examples?

Content Type	Original Author	Original Content on Stackoverflow
Question	Kokizzu	View Question on Stackoverflow
Solution 1 - Function	Kokizzu	View Answer on Stackoverflow

How to pass variable length arguments as arguments on another function in Golang?

Function Problem Overview

Function Solutions

Solution 1 - Function

Compiler not detecting obviously uninitialized variable

Chrome stalls when making multiple requests to same resource?

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