Understanding the Template Method Pattern in Ruby

When I first learned to code, I didn’t think much about structure. I’d write everything in one file, step after step, until something worked. But as my projects grew, that approach started to break down. Simple changes took longer. Adding new features felt risky. I often found myself hunting through messy code just to make a small fix.

Over time, I realized that good structure isn’t just about writing less code it’s about making decisions easier. A well-organized project is easier to change, debug, and understand when I come back to it weeks or months later. That’s what led me to explore design patterns.

In this post, I’ll walk through one pattern that has helped me the most and show how it changed the way I think about building flexible, maintainable Ruby code.

What Is a Design Pattern?

A design pattern is a reusable solution to a common coding problem. It’s not a copy-and-paste chunk of code. Instead, it’s a general approach to organize logic that’s proven to work well in certain situations.

Patterns help us think more clearly. They reduce guesswork. Rather than inventing a new structure every time, we can lean on techniques other developers have used before us. That makes our code easier to understand, both for ourselves and for anyone else reading it.

Template Method Pattern

The Template Method pattern stood out to me. The name sounded formal, but the idea behind it was simple: define the steps of a process in one place, and let the details vary in others.

In practice, this means writing a base class that outlines the structure of a task step by step. Some of those steps are fixed. Others are left open, to be filled in by subclasses.

I started using this pattern when I noticed I was repeating the same general logic in different parts of a project, with only slight differences. Instead of rewriting the full process each time, I used the Template Method to define the shared steps once, then filled in the changing parts as needed.

This made my code easier to manage. When something needed to change, I only touched the part that was different. The rest stayed consistent. It saved me time and helped me avoid bugs.

What I like about the Template Method is that it gives structure without being rigid. I get a clear routine, but still have the flexibility to adapt the details. That balance is why I keep coming back to it.

Breaking it Down

To explain how the Template Method works, I like to start with a simple example. Making a sandwich. It’s a familiar process, and it maps well to how the pattern works in code.

Imagine a general recipe for a sandwich: place the bottom slice of bread, add a filling, then place the top slice. That routine stays the same no matter what kind of sandwich you’re making.

In Ruby, I’d create a class called Sandwich with a method named make. This method defines the sequence of steps. One of those steps (adding the filling) is left blank so subclasses can define their own version.

class Sandwich
  def make
    lay_out_bottom_bread
    add_filling
    lay_out_top_bread
  end

  def lay_out_bottom_bread
    puts "Placing bottom slice of bread."
  end

  def lay_out_top_bread
    puts "Placing top slice of bread."
  end

  def add_filling
    raise NotImplementedError, "Please define the filling!"
  end
end

Now let’s say I want to make a peanut butter sandwich. I’d write a class that inherits from Sandwich and fills in the missing step.

class PeanutButterSandwich < Sandwich
  def add_filling
    puts "Spreading peanut butter."
  end
end

I could make other sandwiches the same way just by changing the add_filling method.

Calling make on a PeanutButterSandwich instance will always follow the same three steps. The bread steps never change, but the filling is different depending on the subclass.

This setup keeps the process consistent while letting me swap in different variations. It avoids repetition and keeps the code easy to follow.

Why I Prefer This Approach

The Template Method pattern became one of my go-to because it helped solve a few common problems in my code.

Less Repetition

Before using this pattern, I often copied and pasted similar blocks of logic with small changes. That made it hard to keep things consistent. If I had to change something, I wasn’t always sure where all the copies were. With the Template Method, the core routine lives in one place. I only change what’s different, which lowers the risk of mistakes.

Easier to Maintain

When I revisit a project months later, it’s clearer what each part does. The structure shows what stays fixed and what varies. I can add new variations by changing one method, not the whole class. That saves time and avoids confusion. A Lesson in Balance

One mistake I made early on was putting too much logic in the base class. That made it harder to create variations, because every subclass started to behave the same. I’ve since learned to keep the base class focused only on the shared process, and let subclasses handle the rest. That keeps the pattern useful and flexible.

Better Collaboration

Structured code is easier for other developers to understand. When someone reads a class that follows a clear pattern, they don’t need to guess how things work. They can follow the steps and focus only on the part that changes. That makes working with others smoother.

In the end, this pattern helps me keep things organized without giving up flexibility. It’s not flashy, but it works, and that’s what I look for when I write code I’ll have to live with later.

When (and When Not) to Use the Template Method

Like any pattern, the Template Method works best in the right context. I’ve found it most useful when there’s a clear routine with small parts that need to change.

When It Works Well

I reach for this pattern when:

• The overall process stays the same, but some steps vary.
• I see similar logic scattered across classes with only slight differences.
• I want to enforce a consistent order of operations while still allowing flexibility.

In those cases, putting the shared steps in a base class keeps my code cleaner. I can then define the unique steps in subclasses, without repeating everything.

When It Doesn’t Fit

I avoid this pattern when:

• Each version of the process is too different to follow the same structure.
• The steps change in number or sequence depending on the case.
• I need more flexibility than inheritance allows.

Overusing the pattern can lead to a long list of subclasses that are hard to manage. If every minor change needs a new class, the code becomes harder to read, not easier.

Other Options

Sometimes, other patterns work better. If I want to swap steps in and out more freely, the Strategy pattern or simple method composition can be a better choice. In general, if inheritance starts to feel like a limitation, I look for alternatives.

My Rule of Thumb

If I see a stable process with small, well-defined points of variation, I consider the Template Method. If the process is unpredictable or highly dynamic, I step back and rethink the structure.

This habit keeps my code honest. I try to choose a pattern that matches the shape of the problem, not just one that looks tidy on the surface.

Final Thoughts

Using the Template Method pattern has changed the way I think about structure in my projects. It gave me a simple way to manage routines that repeat with small differences. Instead of rewriting logic, I now look for ways to define what stays the same and isolate what changes.

One shift I noticed is how I now pause when I see repetition. If I’m doing the same steps with just slight changes, I stop and ask whether a pattern like this one can bring order. That small habit has made my code easier to maintain and easier to extend.

It also helped me work better with others. A clear pattern means less explaining. When structure is built in, the code speaks for itself. That makes collaboration smoother, especially when coming back to code after some time.

Most of all, it’s given me more confidence. Patterns like this don’t solve every problem, but they’ve helped me write code that I trust code that stays out of my way when I need to build, and helps me find issues when things go wrong.