When developers read code, they’re not just parsing syntax — they’re navigating a mental map.

This is especially true in large systems where onboarding new team members or scanning unfamiliar code is routine. One of the more subtle but effective ways to improve that map is through how we order constructor dependencies.

Specifically, placing core framework dependencies like ILogger or IConfiguration first, and deferring to more specific or “exotic” dependencies later, can serve as a powerful, silent guide to any developer reading the code.

The Constructor as a Cognitive Map

When encountering a class for the first time, developers often begin at the constructor. It’s one of the few places where a class’s external contracts and internal wiring are immediately visible.

This means the order in which dependencies are presented matters — not to the compiler, but to the human eye.

By intentionally placing common or foundational dependencies like ILogger, IConfiguration, or IServiceProvider at the top, you’re sending a clear signal: these are part of the standard infrastructure. These are the parts you’ll find in nearly every class.

As you move further down the constructor’s parameter list, you transition into domain-specific or context-heavy dependencies—those used only in this class or a narrow subset of the application.

What’s the big deal?

Following this approach helps in a number of ways for Future Authors (including yourself):

  1. Visual Hierarchy: Like reading a book or scanning a webpage, readers form an impression based on what they see first. Beginning with universal or highly familiar dependencies builds context quickly.
  2. Cognitive Load Reduction: New or unfamiliar dependencies introduced lower in the list signal, “You can skip this for now unless you’re digging into this specific implementation.” This triage helps developers filter information as they go.
  3. Consistent Scanning Across Codebases: If the entire team adopts this convention, it makes reading constructors consistent. It becomes easier to visually scan across multiple files, speeding up onboarding and improving maintenance efficiency.
  4. Signal of Intent: When dependencies are deliberately ordered, it shows thoughtfulness in design. It makes implicit what the team considers “core” vs. “specific.”

Before and After: A Small Change with Big Impact

Let’s look at a tangible example. Here is my constructor before applying this approach. Our dependencies are unordered and all mixed up.

public MyEventProcessor(
    EventHubConsumerClient consumerClient,
    ILogger<MyEventProcessor> logger,
    CustomAnalyticsService analyticsService,
    IConfiguration config,
    InternalMetricsHandler metricsHandler)

This ordering feels arbitrary. A developer encountering this for the first time has no guidance on what’s standard and what’s specific to this implementation.

Lets fix it by ordering the dependencies based on importance and generality:

public MyEventProcessor(
    ILogger<MyEventProcessor> logger,
    IConfiguration config,
    EventHubConsumerClient consumerClient,
    InternalMetricsHandler metricsHandler,
    CustomAnalyticsService analyticsService)

Now, there’s a visual and conceptual hierarchy. The logging, configuration, shared dependencies (like Event publishing) dependencies — used across the application — come first. More exotic and domain-specific services follow. The developer can choose to skim or dive based on context.

Ordering as Communication

Dependency injection ordering is a low-cost, high-value habit. It costs nothing to implement but communicates architectural intent with every constructor. It allows your code to be “read” like a well-organized outline: common infrastructure first, specialized tools later.

In the same way that well-structured Terraform files prioritize foundational resources at the top and exotic configurations later, constructor dependency ordering can provide a quiet but firm sense of structure. It reflects an intentional architecture and a respect for the reader’s time.

Conclusion

Constructor parameter order isn’t just a mechanical detail — it’s a form of communication. Treat your constructors like a map: start with landmarks everyone knows, then guide the reader to the local paths and hidden shortcuts. By doing so, you’ll make your code easier to read, easier to onboard into, and easier to maintain.

Put simply: start with the standard, end with the specific. Let your dependency order guide the way.

Then again, maybe I am just OCD.

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