# Readability and cyclomatic complexity of database transaction code

I consider these two options exactly the same. I prefer the first one but I'm not sure if it's better than the second option in terms of cyclomatic complexity or readability.

Assuming that this is not pure Ruby and I can call to the try method.

existing_transaction = database.find_transaction_by_id(transaction.id)
database.create_transaction(transaction) unless existing_transaction
database.update_transaction(transaction) unless existing_transaction.try(:processed)

existing_transaction = database.find_transaction_by_id(transaction.id)
if existing_transaction
unless existing_transaction.processed
database.update_transaction(transaction)
end
else
database.create_transaction(transaction)
end
-

It's obviously subjective, but IMHO inline conditionals make code harder to understand, indentation is very important. So I'd definitely take the second approach, but writing it differently to use only one indentation level:

existing_transaction = database.find_transaction_by_id(transaction.id)
if !existing_transaction
database.create_transaction(transaction)
elsif !existing_transaction.processed
database.update_transaction(transaction)
end
-

I would actually take a mixed approach:

if existing_transaction
database.update_transaction(transaction) unless existing_transaction.processed
else
database.create_transaction(transaction)
end

This way the code is more readable than the first option, but more succinct than the second option.

-
This is exactly my solution wrote with unless inlined. –  Arturo Herrero Mar 15 at 19:57
Yes, it is - it just reads better IMHO –  Uri Agassi Mar 15 at 20:18