Console provides a consistent cross platform logging and debugging API. The API is consistent with that of the WebKit console. Developers can:

• redirect calls to "trace" to the console
• log messages at different levels
• print stack traces
• inspect structured objects in the WebKit console
• log multiple values in a single trace
• make assertions that trigger errors when they fail
• count invocations at positions within their code
• visually group log messages
• use timers to measure program performance
• start and stop profiling where available
• log Haxe objects in way that is easily inspectable in the WebKit console
• insert breakpoints (on supported platforms)

Console currently supports a number compile time modes:

• On system platforms (neko/php/cpp/nodejs) console prints to stdout, colorising output
• In JS/Flash running in WebKit browser console prints to WebKit console
• In JS running in non-webkit browser console prints to an element in the DOM
• In Flash running standalone or in a non-WebKit browser console prints to an on screen logging panel.
• When the compiler flag no_console is set, the console inlines null expressions, removing any runtime overhead from logging.

Example Usage:

You can download an example of mconsole usage here.

To enable the console, call:

Console.start();

To log a message at a named level:

trace("log", "Something happened.");
trace("info", "Something interesting happened.");
trace("debug", "WHY WON'T YOU WORK!!");
trace("warn", "I didn't test this code at all...");
trace("error", "Something bad happened.");

Messages default to LogLevel.log:

trace("Logtastic");

Log multiple values using trace. In WebKit console each value is inspectable (rather than concatenating as a string)

trace("string", 10, {key:"value"});

You can also call the logging API directly:

Console.log("better than bad, it's good!");

Errors will print a message, then a stack trace:

Console.error("Epic fail");

Outputs:

Error: Epic fail
@ SomeClass.someMethod:20
@ SomeOtherClass.someOtherMethod:48

You can also use Console.trace to print a stack trace without triggering an error:

Console.trace();

Outputs:

Stack trace:
@ SomeClass.someMethod:20
@ SomeOtherClass.someOtherMethod:48

Assertion will print a message and stack trace, then throw and exception when the condition is false:

Console.assert(foo == false, "foo is not false!!");

Outputs:

Assertion failed: foo is not false
@ SomeClass.someMethod:20
@ SomeOtherClass.someOtherMethod:48

To count the number of times a line of code is invoked:

function someCode()
{
	Console.count("apples");
}

someCode();
someCode();

Outputs:

apples: 1
apples: 2

Note that counters are identified by their position, not their label:

Console.count("apples");
Console.count("apples");

Outputs

apples: 1
apples: 1

To insert a breakpoint in JavaScript or Flash:

Console.enterDebugger();

Group log messages together visually:

Console.group("Group");
Console.log("grouped log");
Console.group("Nested group");
Console.warn("nested warn");
Console.groupEnd();
Console.groupEnd();

Output:

Group
  grouped log
  Nested Group
    nested warn

Timers can be used to quickly monitor runtime performance:

Console.time("munging");
for (i in 0...4200000000) munge();
Console.timeEnd("munging");

Output:

munging: 2410ms

JavaScript/Webkit only

The WebKit profiler can be started and stopped:

Console.profile("performance");
var f = function(x) { return x * x; }
var x = f(10);
Console.profileEnd("performance");

And markers added to the WebKit timeline view:

Console.markTimeline("finished");

Type conversion

As the WebKit console has user friendly structure inspection, console will try to convert native Haxe values into something inspectable where possible:

// inspectable XML dom
Console.log(Xml.parse("<this><is><some><xml/><with/><elements/></some></is></this>"));

// enums and enums with parameters
Console.log(value1);
Console.log(value2(33));
Console.log(value3({oooh:"fancy"}));

// mapes
var map = new StringMap<String>();
map.set("mapy", "goodness");
Console.log(map);

var intMap = new IntMap<String>();
intMap.set(10, "int mapy goodness");
Console.log(intMap);

// and iterable objects in general
var list = new List<String>();
list.add("support for iterables in general");
list.add("also good");
Console.log(list);

Printer

Printing is implemented by a mconsole.Printer. Custom printers can be used:

Console.addPrinter(new MyConsolePrinter());

A default printer is always created. This is a ConsoleView for JavaScript and Flash, or a FilePrinter for system targets.

To implement a custom printer:

/**
A ConsolePrinter that raises an alert for each log message.
*/
class AlertConsolePrinter implements mconsole.Printer
{
	public function print(level:mconsole.LogLevel, params:Array<Dynamic>, indent:Int, pos:PosInfos):Void
	{
		js.Lib.alert(Std.string(level) + "@" + pos.className + "." + pos.methodName + ":" + params.join(", "));
	}
}

Caveats

When logging to the WebKit console (JavaScript in a WebKit browser) redirected traces will not display the correct source position in the console panel. The position of the Console.haxeTrace will be shown instead. This is a limitation of the Haxe logging API.

Flash targets can talk to the WebKit console over external interface, but messages will not show the correct position. Use a ConsoleView if you require log positions.