A. Sundararajan's Weblog

using namespace in JavaScript

This is continuation of my earlier post on namespaces. We saw how to implement namespace for JavaScript. How about a feature equivalent to Java's import (or C++ using)? We can implement something like:

/**
 * imports all or subset of names from given namespace.
 *
 * @param ns namespace
 * @param patten names matching this pattern will be imported
 * pattern is optional. If not specified, all names are 
 * imported (like Java's import package_name.*).
 */
function using(ns, pattern) {    
    if (pattern == undefined) {
        // import all
        for (var name in ns) {
            this[name] = ns[name];
        }
    } else {
        if (typeof(pattern) == 'string') {
            pattern = new RegExp(pattern);
        }
        // import only stuff matching given pattern
        for (var name in ns) {
            if (name.match(pattern)) {
                this[name] = ns[name];
            }
        }       
    }
}

var ns = namespace("function p() { print('p'); }; function s() { print('s'); }");
ns.p();    // call 'p' in namespace 'ns'
using(ns); // import all from namespace 'ns'
p();       // call ns.p()
s();       // call ns.s();

var ns = namespace("function p() { print('p'); }; function s() { print('s'); }");
ns.p();           // call 'p' in namespace 'ns'
using(ns, /p.*/); // import only the names matching 
p();              // call ns.p()
ns.s();           // call ns.s() -- but can only use qualified name

( Nov 19 2005, 10:50:50 AM IST ) Permalink Comments [1] | | | | |