underscore.template-helpers.js

(function() {
	var originalUnderscoreTemplateFunction = _.template;
	var templateHelpers = {};

	_.mixin( {
		addTemplateHelpers : function( newHelpers ) {
			_.extend( templateHelpers, newHelpers );
		},

		template : function( text, data, settings ) {
			// replace the built in _.template function with one that supports the addTemplateHelpers
			// function above. Basically the combo of the addTemplateHelpers function and this new
			// template function allows us to mix in global "helpers" to the data objects passed
			// to all our templates when they render. This replacement template function just wraps
			// the original _.template function, so it sould be pretty break-resistent moving forward.

			if( data ) {
				// if data is supplied, the original _.template function just returns the raw value of the
				// render function (the final rentered html/text). So in this case we just extend
				// the data param with our templateHelpers and return raw value as well.

				_.defaults( data, templateHelpers ); // extend data with our helper functions
				return originalUnderscoreTemplateFunction.apply( this, arguments ); // pass the buck to the original _.template function
			}
			
			var template = originalUnderscoreTemplateFunction.apply( this, arguments );

			var wrappedTemplate = function( data ) {
				data = _.defaults( {}, data, templateHelpers );
				return template.call( this, data );
			};

			return wrappedTemplate;
		}
	} );
} )();