CODEWITHSUNDEEP
oopdependency-injectionconstructorrefactoring
redcurry
redcurry

Reputation: 2497

How can I refactor a constructor so its real dependencies are clear?

Let's say that class PersonList has the method AddNewPerson(), which creates and adds a new Person to an internal list. However, the constructor of Person requires several parameters (mostly interfaces it depends on). This means that PersonList will also require to have those parameters passed to its constructor (or somehow made available).

This arrangement seems like a code smell because PersonList doesn't use any of those dependencies directly. It simply passes them along to another's constructor. How may I refactor these classes so that it's clear what the real dependencies are for each class?

Upvotes: 0

Views: 34

Answers (1)

plalx
plalx

Reputation: 43718

"This means that PersonList will also require to have those parameters passed to its constructor (or somehow made available)."

Why would that be? PersonList doesn't have to be a factory for Person objects, you can pass Persons directly to AddNewPerson instead.

E.g.

public void AddNewPerson(Person person);

However, if you both wishes to relieve the client code from creating Person instances and at the same time you want to avoid having PersonList to depend on what's needed to create Persons then you may introduce a PersonFactory that would encapsulate the creation logic as well as the dependencies needed.

In that case the client can either use the PersonFactory to create Persons and add them to the list or the PersonList can depend on the PersonFactory.

Upvotes: 1

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