A module exhibits procedural cohesion when its elements have been grouped together because they always execute in a particular sequence. For example, payment processing for a customer placing an order might involve the following steps being executed in a particular sequence:
- Gathering payment information
- Validating payment method details
- Checking whether funds are available or whether there is enough available credit
- Persisting the order in a database
- Checking inventory levels
- Creating a back order or canceling an order based on inventory
- Sending the order for fulfillment
- Sending an email confirmation to the customer
Although the various parts are all related by the order of execution, some of the individual activities are quite distinct from each other.
This type of cohesion is considered moderate. Although it is an acceptable level of cohesion, it is not ideal. If possible, refactoring can be performed to improve the level of cohesion.