Two things are different:

 1. Printing via package log is safe from concurrent goroutines (while plain `fmt` isn&#39;t)

 2. Log can add timing information automatically.

So these are two completely different things. log is for logging and `fmt` for formatting. (Okay, log uses the same verbs and flags, but that is just convenient).


How can user defined functions (say `f`) have meaningful printouts when inspected via the REPL using `?f`or `help(f)`

For example imagine I write the following funciton

    function f(x::Float64, y::Float64)
        return 2x - y^2
    end

If I load this into a julia session and try `help(f)` I get the following:

    julia&gt; help(f)
    f (generic function with 1 method)

What if instead I wanted to see something like

    julia&gt; help(f)
    f

       Compute 2 times x minus y squared

where the description &quot;Compute 2 times x minus y squared&quot; is written somewhere. I am guessing the answer to my question can be determined from the answer to the question &quot;Where is the somewhere the description should be written?&quot;

---

By way of example, if I wanted to do the same in python, I could define the function and put the description as a docstring:

    def f(x, y):
        &quot;&quot;&quot;
        Compute 2 times x minus y squared
        &quot;&quot;&quot;
        return 2 *  x - y ** 2

which would make my description immediately available when I type `help(f)` or `f?` from IPython.


How to make user defined function descriptions (&quot;docstrings&quot;) available to julia REPL?

I have been playing about with the new MVC 5, I have a few models, controller and views setup using code first migrations. 

My question is how do I seed users and roles? I currently seed some reference data in my Seed method in Configuration.cs. But it looks to me that the user and roles tables are not created until something first hits the AccountController. 

I currently have two connection strings so I can separate my data from my authentication into different databases.

How can I get the user, roles, etc tables populate along with my others? And not when the account controller is hit?


MVC 5 Seed Users and Roles

From [log.go][1] (the implementation of the log package) : 

    167	// Println calls l.Output to print to the logger.
    168	// Arguments are handled in the manner of fmt.Println.
    169	func (l *Logger) Println(v ...interface{}) { l.Output(2, fmt.Sprintln(v...)) }

[`log.Println`][2] is just a function wrapper for [`fmt.Sprintln`][3] , why should I use it instead of [`fmt.Println`][4] or [`fmt.Sprintln`][3] ?

Any practical reasons ?

  [1]: http://golang.org/src/pkg/log/log.go
  [2]: http://golang.org/pkg/log/#Println
  [3]: http://golang.org/pkg/fmt/#Sprintln
  [4]: http://golang.org/pkg/fmt/#Println

Why should I use log.Println instead of fmt.Println?

From <a href="http://golang.org/src/pkg/log/log.go" target="_blank" rel="noopener noreferrer">log.go</a> (the implementation of the log package) :
<pre><code class="hljs language-scss">167	// Println calls l.Output to print to the logger.
168	// Arguments are handled in the manner of fmt.Println.
169	func (l *Logger) Println(v ...interface{}) { l.Output(2, fmt.Sprintln(v...)) }
</code></pre>
<a href="http://golang.org/pkg/log/#Println" target="_blank" rel="noopener noreferrer"><code>log.Println</code></a> is just a function wrapper for <a href="http://golang.org/pkg/fmt/#Sprintln" target="_blank" rel="noopener noreferrer"><code>fmt.Sprintln</code></a> , why should I use it instead of <a href="http://golang.org/pkg/fmt/#Println" target="_blank" rel="noopener noreferrer"><code>fmt.Println</code></a> or <a href="http://golang.org/pkg/fmt/#Sprintln" target="_blank" rel="noopener noreferrer"><code>fmt.Sprintln</code></a> ?
Any practical reasons ?

I am building an application based on expressjs and I&#39;d like to log all events in it. I could find winston, which seems to be cool. Anyway, I am looking for a way how to connect it to my expressjs app.

What I also want is logging inside the application. My reqeusts are not so simple, so I&#39;d like to log everything inside my app (not only requests).

My current situation:

**server.js** (I&#39;d like to log http requests on this level)

    var express = require(&#39;express&#39;);
    var app = express();
    var fs = require(&#39;fs&#39;);
    
    // Post parser
    app.configure(function(){
        app.use(express.bodyParser());
    });

    // Load routes
    require(&#39;fs&#39;).readdirSync(__dirname + &#39;/routes&#39;).forEach(function(file) {
        require(__dirname + &#39;/routes/&#39; + file)(app);
    });

    // 404: Not found
    app.use(function(req, res, next){
        res.json(404, {ERROR: &#39;Page not found.&#39;});
    });

    // 500: Error reporing
    app.use(function(err, req, res, next){
        console.error(err.stack);
        res.json(500, {ERROR: &#39;Internal server error.&#39;} );
    });
    
    // Startup new server
    app.listen(900);

**routes/something.js**

    var something = require(__dirname + &#39;/../controller/something.js&#39;);
    
    module.exports = function(app) {
        app.get(&#39;/v1/something&#39;, function(req, res, next) { new something().getAll(req, res, next); });
    };

**controller/something.js** (I&#39;d like to use the same logger for debug logging)

    /**
     * Constructor
     *
     */
    function Something() {
    };
    
    /**
     * Get all the data
     *
     */
    Something.prototype.getAll = function(req, res, next) {
        // I want to log some very important information here
        res.json({result: true, data: [&#39;hello&#39;, &#39;hi&#39;, &#39;ciao&#39;, &#39;buf&#39;]});
    }
    
    module.exports = Something;

The other thing I am thinking about is logging all the events in functions that are called from controllers (e.g. models or other libraries).

So I think, the good way might to create some logger library, that will be called using:

    var logger = require(__dirname + &#39;/../libraries/logger.js&#39;);

containing logger definition. The other issue I don&#39;t know how to solve is how to prefix data. You know, I have a lot of concurrent requests and I&#39;d like to see which debug message was called by each request.


What&#39;s the best practice for expressjs logging?

I&#39;m trying to write to a log file with Go.

I have tried several approaches, all of which have failed. This is what I have tried:


    func TestLogging(t *testing.T) {
        if !FileExists(&quot;logfile&quot;) {
            CreateFile(&quot;logfile&quot;)
        }
        f, err := os.Open(&quot;logfile&quot;)
        if err != nil {
            t.Fatalf(&quot;error: %v&quot;, err)
        }

        // attempt #1
        log.SetOutput(io.MultiWriter(os.Stderr, f))
        log.Println(&quot;hello, logfile&quot;)

        // attempt #2
        log.SetOutput(io.Writer(f))
        log.Println(&quot;hello, logfile&quot;)

        // attempt #3
        log.SetOutput(f)
        log.Println(&quot;hello, logfile&quot;)
    }

    func FileExists(name string) bool {
        if _, err := os.Stat(name); err != nil {
           if os.IsNotExist(err) {
                return false
            }
        }
        return true
    }

    func CreateFile(name string) error {
        fo, err := os.Create(name)
        if err != nil {
            return err
        }
        defer func() {
            fo.Close()
        }()
        return nil
    }

The log file gets created, but nothing ever gets printed or appended to it. Why?

How to write log to file

How would I write a log file in c#?

Currently i have a timer with this statement which ticks every 20 secs:

    File.WriteAllText(filePath+&quot;log.txt&quot;, log);

For everything that i want logged i do this: 

    log += &quot;stringToBeLogged&quot;;

As you can assume the string log just grows and grows as the program runs. (I don&#39;t even know if there is a maximum chars per string?)

I assume that there must be better ways of doing this. i just thought that it would be heavy to write the whole file again and again for every time something is added to the log.

How to write log file in c#?

I have the following lines of code that initialize logging.
I comment one out and leave the other to be used. 
The problem that I&#39;m facing is that the one that is meant to log to the file not logging to file. It is instead logging to the console.
Please help.

## For logging to Console:

    logging.basicConfig(level=logging.INFO,
            format=&#39;%(asctime)s [%(levelname)s] (%(threadName)-10s) %(message)s&#39;,)



## for file logging

    logging.basicConfig(filename=&#39;server-soap.1.log&#39;,level=logging.INFO,
            format=&#39;%(asctime)s [%(levelname)s] (%(threadName)-10s) %(message)s&#39;)

python logging file is not working when using logging.basicConfig

I&#39;m using PyCharm to develop a GAE app in Mac OS X. Is there any way to display colours in the run console of PyCharm?

I&#39;ve set a [handler][1] to output colours in ansi format. Then, I&#39;ve added the handler:

    LOG = logging.getLogger()
    LOG.setLevel(logging.DEBUG)
    for handler in LOG.handlers:
        LOG.removeHandler(handler)
    
    LOG.addHandler(ColorHandler())

    LOG.info(&#39;hello!&#39;)
    LOG.warning(&#39;hello!&#39;)
    LOG.debug(&#39;hello!&#39;)
    LOG.error(&#39;hello!&#39;)

 But the colour is the same.

![PyCharm run console output][2]

EDIT:

A response from JetBrains [issue tracker][3]: Change line 55 of the snippet from sys.stderr to sys.stdout. stderr stream is always colored with red color while stdout not.

Now colours are properly displayed.


  [1]: http://xsnippet.org/359377/
  [2]: http://i.stack.imgur.com/130xo.png
  [3]: http://youtrack.jetbrains.com/issue/PY-11543

PyCharm logging output colours

Is there an elegant way in Go to do multiple assignments from arrays like in Python? Here is a Python example of what I&#39;m trying to do (split a string and then assign the resulting array into two variables).

    python:
    &gt;&gt;&gt; a, b = &quot;foo;bar&quot;.split(&quot;;&quot;)

My current solution is:

    x := strings.Split(&quot;foo;bar&quot;, &quot;;&quot;)
    a, b := x[0], x[1]

I&#39;m can see this getting messy in some constructs. The practical example I&#39;m currently facing is a bookmark file parsing and assigning to a map:

    bookmark := make(map[string]string)
    x := strings.Split(&quot;foo\thttps://bar&quot;, &quot;\t&quot;)
    name, link := x[0], x[1]
    bookmark[name] = link

Now I have a useless variable `x` sitting around. I&#39;d like to do something like:

    bookmark := make(map[string]string)
    name, line := strings.Split(&quot;foo\thttps://bar&quot;, &quot;\t&quot;)
    bookmark[name] = link

but that&#39;s invalid.

Unpack slices on assignment?

Here&#39;s what I&#39;m currently using, which I think gets the job done, but there&#39;s got to be a better way:

    func isWindows() bool {
    	return os.PathSeparator == &#39;\\&#39; &amp;&amp; os.PathListSeparator == &#39;;&#39;
    }

As you can see, in my case all I need to know is how to detect windows but I&#39;d like to know the way to detect any platform/os.

Play:

http://play.golang.org/p/r4lYWDJDxL

How to reliably detect os/platform in Go

I want to return an error from a function if it panics (in Go):

    func getReport(filename string) (rep report, err error) {
    	rep.data = make(map[string]float64)

    	defer func() {
    		if r := recover(); r != nil {
    			fmt.Println(&quot;Recovered in f&quot;, r)
    			err, _ = r.(error)
                return nil, err
			}
    	}()
    	panic(&quot;Report format not recognized.&quot;)
        // rest of the getReport function, which can try to out-of-bound-access a slice
        ...
    } 


I appear to have misunderstood the very concept of panic and defer. Can anybody enlighten me?


Go: returning from defer

In C/C++ (and many languages of that family), a common idiom to declare and initialize a variable depending on a condition uses the ternary conditional operator :

    int index = val &gt; 0 ? val : -val

Go doesn&#39;t have the conditional operator. What is the most idiomatic way to implement the same piece of code as above ? I came to the following solution, but it seems quite verbose

    var index int

    if val &gt; 0 {
        index = val
    } else {
        index = -val
    }

Is there something better ?

Content Type	Original Author	Original Content on Stackoverflow
Question	Salah Eddine Taouririt	View Question on Stackoverflow
Solution 1 - Logging	Volker	View Answer on Stackoverflow

Why should I use log.Println instead of fmt.Println?

Logging Problem Overview

Logging Solutions

Solution 1 - Logging

MVC 5 Seed Users and Roles

How to make user defined function descriptions ("docstrings") available to julia REPL?

Attributions