Pragmatic directives: Difference between revisions

=={{header|Wren}}==

The closest thing Wren has to a pragmatic directive is its '''import''' statement which loads a module, executes its source code and imports variable names from that module into the current scope.

Import statements can appear anywhere a variable declaration is allowed and in particular within conditional structures. This enables us to do things such as the following:

<lang ecmascript>/* windows.wren */

class Windows {

static message { "Using Windows." }

static lineSeparator { "\\r\\n" }

}</lang>

<lang ecmascript>/* linux.wren */

class Linux {

static message { "Using Linux." }

static lineSeparator { "\\n" }

}</lang>

<lang ecmascript>/*pragmatic_directives.wren*/

import "os" for Platform

var os

if (Platform.isWindows) {

import "/windows" for Windows

os = Windows

} else {

import "/linux" for Linux

os = Linux

}

System.print("%(os.message) which has a \"%(os.lineSeparator)\" line separator.")</lang>

{{out}}

From the last script, when run on a Linux system.

<pre>

$ wren_cli pragmatic_directives.wren

Using Linux which has a "\n" line separator.

</pre>