The "params" Map of TemplateDirectiveModel

Hi,

I'm currently writing a bunch of TemplateDirectiveModel implementations, and as part of the parameters validation, I was wondering if it was considered "safe" or even good practice to manipulate the params map. What I had in mind is: get/convert parameters and remove them from the map as I go (using utility method which take care of checking types, throwing exception with adequate messages etc - see below); once I fetched all my parameters, I should be able to do something along the lines of:
if (!params.isEmpty())
  throw new TemplateModelException("unsupported parameter(s): " + params);

Any thought or advice ? Would this be a decent way to go, or is there something easier I could do ?

Cheers,

-greg

ps: for the record: all my directives extend a custom Abstract one, which has a _param() method (see below) and other simpler protected methods which eventually all delegate to _param(), such as:

    protected String mandatoryString(Map params, String key) throws TemplateModelException {
        return _param(params, key, TemplateScalarModel.class, true).getAsString();
    }

    // [...] other param* methods [...]

    protected <MT extends TemplateModel> MT _param(Map<String, TemplateModel> params, String key, Class<MT> type, boolean isMandatory) throws TemplateModelException {
        if (isMandatory && !params.containsKey(key)) {
            throw new TemplateModelException("The '" + key + "' parameter is mandatory.");

        }
        final TemplateModel m = params.get(key);
        if (m != null && !type.isAssignableFrom(m.getClass())) {
            throw new TemplateModelException("The '" + key + "' parameter must be a " + type.getSimpleName() + " and is a " + m.getClass().getSimpleName() + ".");
        }
        if (m == null && params.containsKey(key)) {
            // parameter is passed but null value ... (happens with content.nonExistingSubNode apparently)
            throw new TemplateModelException("The '" + key + "' parameter was passed but not or wrongly specified.");
        }

        return (MT) m;
    }




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