# Óg [](https://travis-ci.org/stephenmoloney/og) [](https://hex.pm/packages/og) [](https://hexdocs.pm/og)
[Óg](http://hexdocs.pm/og/Og.html) is a small collection of debugging functions for use during development.
### Note
- Functions `Og.log/2` and `Og.log_r/2` are debugging tools for use during development only.
### Installation
Add óg to your list of dependencies in `mix.exs`:
```elixir
def deps, do: [{:og, "~> 1.0"}]
```
Ensure that `:logger` is started in the applications:
```elixir
def application do [applications: [:logger]] end
```
## Summary
- `log/2` - logs the data transformed by the inspector function
and returns `:ok`
- `log_r/2` - logs the data transformed by the inspector function
and returns the original data.
- Inspection of the data before logging it can be helpful in a debugging context for
- Avoiding the `Protocol.UndefinedError` when logging tuples for example.
- Not needing to require Logger
- However, the functions `Og.log/2` and `Og.log_r/2` should be reserved for
debugging code only in `:dev` environments and should not
be used in production because:
- Formatting the data carries an overhead.
- Example configuration of the `Logger`
```elixir
use Mix.Config
config :logger,
backends: [:console],
level: :debug,
compile_time_purge_level: :debug,
compile_time_application: :my_app,
truncate: (4096 * 8),
utc_log: :false
config :logger, :console,
level: :debug,
format: "$time $metadata [$level] $message\n",
metadata: []
config :logger, :og,
kernel_opts: [width: 70],
apex_opts: [numbers: :false, color: :false]
```
### some examples
- Basic logging
```elixir
Og.log(:test)
```
- Logging at the `:warn` level
```elixir
Og.log(:test, level: :warn)
```
- Logging at the `:warn` level and with __ENV__ specified to get richer information
```elixir
Og.log(:test, level: :warn, env: __ENV__)
````
- Logging with the Apex inspector
```elixir
Og.log(:test, inspector: :apex)
```
- Logging inside a chain of piped functions
```elixir
defmodule OgTest do
def log() do
%{first: "john", last: "doe"}
|> Map.to_list()
|> Enum.filter( &(&1 === {:first, "john"}))
|> Og.log_r()
|> List.last()
|> Tuple.to_list()
|> List.last()
|> Og.log_r(env: __ENV__, inspector: :kernel, level: :info)
|> String.upcase()
end
end
OgTest.log()
```
### Acknowledgements
- Credit to [Björn Rochel](https://github.com/BjRo) for the [Apex library](https://github.com/BjRo/apex).
Setting opts to `[inspector: :apex]` will use the `Apex.Format.format/2` function from the apex library.
### Todo
- [ ] Investigate adding a custom formatting module as an optional additional means of logging.
### Licence
MIT
