Convention over configuration

Disadvantages of the convention over configuration approach can occur due to conflicts with other software design principles, like the Zen of Python's "explicit is better than implicit."

A software framework based on convention over configuration often involves a domain-specific language with a limited set of constructs or an inversion of control in which the developer can only affect behavior using a limited set of hooks, both of which can make implementing behaviors not easily expressed by the provided conventions more difficult than when using a software library that does not try to decrease the number of decisions developers have to make or require inversion of control.

Other methods of decreasing the number of decisions a developer needs to make include programming idioms and configuration libraries with a multilayered architecture.

For example, early versions of the Java persistence mapper Hibernate mapped entities and their fields to the database by describing these relationships in XML files.

Later versions did away with the XML configuration file and instead employed these very conventions, deviations from which can be indicated through the use of Java annotations (see JavaBeans specification, linked below).