Adapter

Adapter

One-line pattern summary

A pattern that converts an incompatible existing interface into the interface expected by the current system.

Typical Unity use cases

• When aligning a legacy or external SDK with the project’s standard API.
• When reusing an existing implementation without modifying it.

Parts (roles)

• Target
• Adaptee
• Adapter

Unity example (C#)

The code below is a simplified Unity example based on the scenario described above.

public interface IAdsService
{
    void ShowRewardedAd(string placementId);
}

public sealed class LegacyAdsSdk
{
    public void ShowRewardVideo(string zoneId) { }
}

public sealed class LegacyAdsServiceAdapter : IAdsService
{
    private readonly LegacyAdsSdk legacyAdsSdk = new();

    public void ShowRewardedAd(string placementId)
    {
        legacyAdsSdk.ShowRewardVideo(placementId);
    }
}

Advantages

• It clarifies module boundaries and reduces coupling.
• Features can be extended or integrated without modifying existing code.

Things to watch out for

• If wrapper layers become too deep, debugging gets harder.
• Interfaces should stay small so responsibility boundaries do not blur.

Interaction diagram

This shows the flow where an existing interface is converted into the target interface for reuse.