🔸 TL;DR
▪️ Message chains leak internals and create fragile coupling.
▪️ Fix by hiding delegates, moving/extracting behavior, or introducing facades/services.
▪️ Follow the Law of Demeter and Tell, Don’t Ask for cleaner, resilient code. ✅( see: https://blog.vvauban.com/blog/law-of-demeter-lod-don-t-talk-to-strangers )
🔸 WHAT IT IS
▪️ A message chain is a call that calls a call that calls a call… (a.b().c().d()), exposing deep object structure.
▪️ You’re reaching through one object to touch another → tight coupling, brittle code. 🧩
🔸 WHY IT’S BAD
▪️ Coupling → bad: A tiny change deep inside breaks callers far away.
▪️ Law of Demeter 🚷: “Only talk to your immediate friends.” Chains talk to friends-of-friends.
▪️ Readability ↓ and mocking/tests get messy (lots of stubs).
▪️ Tell, don’t ask: Chains ask for internals instead of telling an object to do work.
🔸 CODE SMELL EXAMPLE
// Message chain
var city = order.getCustomer().getAddress().getCity();
🔸 BETTER OPTIONS
▪️ Hide Delegate (inverse of Middle Man):
// Order hides the delegate
public String getCustomerCity() { return customer.getAddress().getCity(); }
// Callers
var city = order.getCustomerCity();
▪️ Extract/Move Function to the rightful owner:
// Tell the object to do it
order.shipToCustomerCity();
▪️ Introduce Facade / Service to wrap traversal and provide intent-revealing API.
▪️ Use DTO/Assembler to flatten read models for queries (CQRS-friendly).
▪️ Sequence of Temps ➡️ Avoid if it’s just chaining getters:
// Not better if it just exposes internals step by step
var c = order.getCustomer();
var a = c.getAddress();
var city = a.getCity();
▪️ Guard Rails: Prefer interfaces that expose behavior, not structure; review chains in PRs; add static analysis rules (e.g., detect get().get() patterns).
🔸 TAKEAWAYS
▪️ Spot it: Look for . repeated 3+ times.
▪️ Name intent: Replace chains with intent-revealing methods.
▪️ Own the behavior: Put logic where the data lives.
▪️ Refactor safely: Add tests, then Hide Delegate / Move Function / Facade.
#CleanCode #Refactoring #LawOfDemeter #TellDontAsk #Java #Spring #SoftwareDesign #CodeSmell #Architecture #OOP #TDD #Craftsmanship
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