Meteor: getting the HTML element which is using a global helper - meteor

Question

Is it possible to know the HTML element which is invoking a global helper?
I have this blaze template:
<template name="tools">
<div>
<a id="pencil" class="{{toolIsActive}}">Pencil</a>
<a id="shape" class="{{toolIsActive}}">Shape</a>
<a id="poly" class="{{toolIsActive}}">Polygon</a>
<a id="arrow" class="{{toolIsActive}}">Arrow</a>
</div>
</template>
and so it'd be useful a helper like this:
UI.registerHelper('toolIsActive', function() {
return (this.id === currentTool) ? 'active' : '';
});
where I want this to be the invoking HTML element instead of template's data context.
Is there a way to access the element? I know I could use this.$('#pencil') but it's useless since the id it's exactly what I want to know.

Answer 1

You can work around this problem by passing the tool name as an argument for the helper:
<a id="pencil" class="{{toolIsActive 'pencil'}}">Pencil</a>
UI.registerHelper('toolIsActive', function(tool) {
return (tool === currentTool) ? 'active' : '';
});
Since this sort of helper is useful in many different parts of the application, you can make an universal one instead:
<a id="pencil" class="{{classIfEqual 'pencil' currentTool 'active'}}">Pencil</a>
UI.registerHelper('classIfEqual', function(a, b, className) {
return (a === b) ? className : '';
});

Answer 2

Another approach, which could make it easier to add more tools in the future:
<template name="tools">
<div>
{{#each tools}}
<a id="{{id}}" class="{{toolIsActive}}">{{humanName}}</a>
{{/each}}
</div>
</template>
Template.tools.helpers({
tools: [
{id: "pencil", humanName: "Pencil"},
{id: "shape", humanName: "Shape"},
{id: "poly", humanName: "Polygon"},
{id: "arrow", humanName: "Arrow"}
],
toolIsActive: function() {
return (this.id === currentTool) ? "active" : ""
}
});
You could potentially use that tools structure in multiple places, and then if you want to add more tools, you only have to add it in one place.