/// <summary>
/// Get the specific metric for a given label.
///
/// If a set of acceptable labels were specified in the metrics.yaml file,
/// and the given label is not in the set, it will be recorded under the
/// special `__other__`.
///
/// If a set of acceptable labels was not specified in the metrics.yaml file,
/// only the first 16 unique labels will be used. After that, any additional
/// labels will be recorded under the special `__other__` label.
///
/// Labels must be snake_case and less than 30 characters. If an invalid label
/// is used, the metric will be recorded in the special `__other__` label.
/// </summary>
/// <param name="label">The label</param>
/// <exception cref="InvalidOperationException">
/// If the type of `T` is currently not supported.
/// </exception>
public T this[string label]
{
get {
// Note the double `(T)(ILabeledSubmetricInterface)` cast before returning. This is
// required in order to make the compiler not complain. Since the `where` clause for
// this class cannot list more than one class, we need all our supported subtypes to
// implement a common interface and use that interface as the T type constraint. This
// allows us to then explicitly cast back to T, which is otherwise impossible.
switch (submetric)
{
case BooleanMetricType _:
{
UInt64 handle = LibGleanFFI.glean_labeled_boolean_metric_get(this.handle, label);
return((T)(ILabeledSubmetricInterface) new BooleanMetricType(handle, disabled, sendInPings));
}
case CounterMetricType _:
{
UInt64 handle = LibGleanFFI.glean_labeled_counter_metric_get(this.handle, label);
return((T)(ILabeledSubmetricInterface) new CounterMetricType(handle, disabled, sendInPings));
}
case StringMetricType _:
{
UInt64 handle = LibGleanFFI.glean_labeled_string_metric_get(this.handle, label);
return((T)(ILabeledSubmetricInterface) new StringMetricType(handle, disabled, sendInPings));
}
default:
throw new InvalidOperationException("Can not get a submetric of this metric type");
}
}
}
