# TelemetryDecorator
[](https://github.com/amplifiedai/telemetry_decorator/actions)
[](https://hex.pm/packages/telemetry_decorator)
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A function decorator for telemetry.
## Usage
defmodule MyApp.MyModule do
use TelemetryDecorator
@decorate telemetry([:my_app, :succeed])
def succeed(arg1, arg2) do
:...
end
end
Because we're using `:telemetry.span/3` under the hood, you'll get these events:
* `[:my_app, :succeed, :start]`
* `[:my_app, :succeed, :stop]`
* `[:my_app, :succeed, :exception]`
Because we're wrapping it with `Decorator`, we can provide more metadata than
`:telemetry.span/3` usually does:
* Any variables matched by your arguments for `:start`, `:stop`, and `:exception` events
* Your function's `result` for `:stop` events (overriding any variable named `result`)
To include more internal variables in your `:stop` events, add the `include` option:
defmodule MyApp.MyModule do
use TelemetryDecorator
def succeed(why), do: succeed(why, [])
@decorate telemetry([:my_app, :succeed], include: [:type])
def succeed(why, opts) do
type = Keyword.get(opts, :type, :ok)
{type, why}
end
end
To watch `:telemetry.span/3` style events at the `iex>` prompt:
handler_id = TelemetryDecorator.watch([:my_app, :succeed])
MyApp.MyModule.succeed(42)
# hang up, or explicitly unwatch:
TelemetryDecorator.unwatch(handler_id)
`TelemetryDecorator.watch/1` sends to remote consoles, too, and with syntax colours. See the
documentation for `Pretty` to find out how.
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## Installation
Add `telemetry_decorator` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:telemetry_decorator, "~> 1.0.0"}
]
end
```
## Development
`make check` before you commit! If you'd prefer to do it manually:
* `mix do deps.get, deps.unlock --unused, deps.clean --unused` if you change dependencies
* `mix compile --warnings-as-errors` for a stricter compile
* `mix coveralls.html` to check for test coverage
* `mix credo` to suggest more idiomatic style for your code
* `mix dialyzer` to find problems typing might reveal… albeit *slowly*
* `mix docs` to generate documentation
