modules.md

title	layout
Modules	default

Neko Modules

Each compiled Neko file is considered its own separate module, with its own scope. Values within the module may be exported by adding it as a field to the global $exports object. $exports will then be available to outside modules.

When importing a module, the local path is searched along with any paths listed in the NEKOPATH environment variable. The paths in NEKOPATH should be separated by colons (:).

Exporting Values

Exporting is quite simple, just add any value that should be made accessible into the $exports object, using any name:

{% highlight javascript %} var s = "hello!";

var f = function(x) { x };

i = 100101;

$exports.hello = s; $exports.identity = f; $exports.number = i; {% endhighlight %}

Importing Values

Values are "imported" by loading in the $exports object from another file and assigning it to a variable. Note that the module which is being loaded will actually be executed as it is loaded. This means the $exports object may be generated dynamically.

To load in a module, there is a global object called $loader with a loadmodule method for loading modules. Keep in mind, however, that modules written in Neko are handled differently than those written in C. For loading C modules, see here.

loadmodule takes two arguments: the name of the module minus the ".n" extension and a loader object. In most cases, the $loader object itself would be used for the second argument.

If the code above were compiled into a file named "test.n", the following code could be used to load it:

{% highlight javascript %} var test = $loader.loadmodule("test", $loader);

$print(test.hello); //prints "hello!"

$print(test.number); //prints "100101"

$print(test.identity("test!")); //prints "test!" {% endhighlight %}

The imported object essentially becomes a shared object between modules, so it is possible to modify an $exports object at runtime and have the changes reflected in another module. The first block of code below is saved in a module named "test" and loaded by the second block of code. The second block of code calls a function in the first, which adds a new exported value. This exported value is then available in the second block of code.

{% highlight javascript %} //test.neko

var add_export = function(x) { $exports.more = x };

$exports.add_export = add_export; {% endhighlight %}

{% highlight javascript %} var test = $loader.loadmodule("test", $loader);

test.add_export("hello!");

$print(test.more); //prints "hello!" {% endhighlight %}

The object returned from loadmodule also includes the field __module which is an abstract value containing information regarding the loaded module. This field can be used in conjunction with the module standard library, documented here.

{% highlight javascript %} var test = $loader.loadmodule("test", load);

var f = $loader.loadprim("std@module_name", 1); $print(f(test.__module)); //prints "test" {% endhighlight %}