Behaviour for evaluation metrics.

All metrics in DeepEvalEx implement this behaviour, which defines the interface for measuring test cases against evaluation criteria.

Implementing a Custom Metric

defmodule MyApp.CustomMetric do
  use DeepEvalEx.Metrics.BaseMetric

  @impl true
  def metric_name, do: "CustomMetric"

  @impl true
  def required_params, do: [:input, :actual_output]

  @impl true
  def measure(test_case, opts) do
    # Your evaluation logic
    score = calculate_score(test_case)
    threshold = Keyword.get(opts, :threshold, 0.5)

    {:ok, DeepEvalEx.Result.new(
      metric: metric_name(),
      score: score,
      threshold: threshold,
      reason: "Explanation..."
    )}
  end
end

Using the using Macro

The use DeepEvalEx.Metrics.BaseMetric macro provides:

• Default implementation of validate_test_case/2
• Telemetry instrumentation around measure/2
• Consistent error handling

You can override any of these defaults.