hirataya/fatechan — comment on commit 1377eb16701fc71ad4e098bc9b6eb9fa1609a52d
File: plugins/calc.rb line 11
By dominikh:

```ruby
set :reacting_on, :channel
match(/^calc[\s:]\s*(.*)/)

def execute(m, expression)
# this will only be called for messages in the channel that match the pattern.
end
```