In the development of complex systems, we often need to face changes in multiple dimensions.Bridge PatternIs a structural design pattern, its main purpose is toSeparation of abstraction from implementation, so that they can change independently. Through the bridge pattern, developers can achieve decoupling of functions in different dimensions, making the system more flexible and scalable. This article will introduce the concept of the bridge pattern in detail, the difference from other similar patterns, the problems it solves, implementation examples in Golang, and precautions in practical applications.

What is Bridge Pattern?

Bridge Mode(Bridge Pattern)abstractandaccomplishSeparate them so that they can change independently. In other words, the bridge pattern builds a bridge for two independent change dimensions. In this way, even if one dimension changes, it will not affect the other dimension, thereby reducing the coupling of the code.

Components of the Bridge Pattern

• Abstraction: Defines the high-level interface to be used by the client.
• Refined Abstraction: The interface of the abstract part is implemented, and the logic of the implementation part can be called.
• Implementor: Defines the underlying interface required to implement the abstract part.
• Concrete Implementor: Provides the specific logic of the implementation part.

With the Bridge pattern, both the abstraction and the implementation can evolve independently without affecting each other.AbstractResponsible for defining business logic, andImplementationResponsible for the specific operation implementation.

The difference between the bridge pattern and other similar patterns

The bridge pattern is similar to some common structural design patterns, such asAdapter Pattern,Combination ModeandDecorative Pattern, there are some similarities, but their purposes and usage scenarios are different.

1. Adapter Pattern:

   • Target: The adapter pattern converts the interface of a class into the interface expected by the client to solve interface incompatibility problems.
   • the difference: The adapter pattern is designed after the fact to adapt existing classes to new interfaces, while the bridge pattern is designed in advance to decouple abstraction and implementation.
     The adapter mode can be viewed in the blog post:Adapter Pattern

2. Composite Pattern:

   • Target: The composite pattern is used to combine objects into a tree structure to represent a "part-whole" relationship.
   • the difference: The composite pattern focuses on the hierarchical relationship of objects, while the bridge pattern focuses on the separation of abstraction and implementation.
     The combiner mode can be viewed in the blog post:Combination Mode

3. Decorator Pattern:

   • Target: The Decorator pattern extends the behavior of an object by dynamically adding new functionality to the object.
   • the difference: The decorator pattern emphasizes the dynamic enhancement of functionality, while the bridge pattern emphasizes the decoupling and flexibility of the structure.
     The decorator pattern can be found in the blog post:Decorative Pattern

What problem does the bridge pattern solve?

The bridge mode mainly solves the following problems:

1. Multi-dimensional changes: When a system needs to change in multiple dimensions (such as multiple platforms and multiple business needs), the bridge pattern can decouple these dimensions so that each dimension can change independently.
2. Reduce the number of classes: Through the bridge pattern, there is no need to create a large number of subclasses for each specific implementation, thus avoiding class explosion.
3. Enhance system scalability: The bridge pattern allows adding new abstractions or implementation parts without modifying existing code, thereby improving the scalability of the system.

Bridge pattern implementation in Golang

The following example shows how to implement the bridge pattern in Golang. Suppose we need to develop a message sending system that supports different message types (such as ordinary messages and emergency messages) and different sending methods (such as SMS and email). The bridge pattern can help us achieve decoupling in the two dimensions of message type and sending method.

Example: Messaging System

1. Define the interface of the implementation part

package main import "fmt" // MessageSender interface: defines the message sending method type MessageSender interface { Send(message string) }

2. Implement specific sending methods

// SMS structure: Send a message via SMS type SMS struct{} func (s *SMS) Send(message string) { fmt.Printf("Sending SMS: %s\n", message) } // Email structure: Send a message via email type Email struct{} func (e *Email) Send(message string) { fmt.Printf("Sending Email: %s\n", message) }

3. Define the interface of the abstract part

// Message interface: define message type type Message interface { SendMessage(content string) }

4. Implement specific message types

// CommonMessage structure: common message type CommonMessage struct { sender MessageSender } func (c *CommonMessage) SendMessage(content string) { c.sender.Send("[Common] " + content) } // UrgentMessage structure: urgent message type UrgentMessage struct { sender MessageSender } func (u *UrgentMessage) SendMessage(content string) { u.sender.Send("[Urgent] " + content) }

5. Example code using the bridge pattern

func main() { // Create a specific sending method sms := &SMS{} email := &Email{} // Create different types of messages and specify the sending methods commonMessage := &CommonMessage{sender: sms} urgentMessage := &UrgentMessage{sender: email} // Send messages commonMessage.SendMessage("Hello, this is a normal message.") urgentMessage.SendMessage("This is an urgent message!") }

Output

Sending SMS: [Common] Hello, this is a normal message. Sending Email: [Urgent] This is an urgent message!

Code Analysis

1. MessageSender Interface: Defines the interface for message sending. Different sending methods (such as SMS and email) implement this interface.
2. CommonMessage and UrgentMessage structures: Represents different types of messages, which are combined MessageSender The interface implements different sending methods.
3. Decoupling of the bridge pattern: Message type and sending method are two independent dimensions, which are decoupled through the bridge pattern so that they can change independently.

Application in actual development

The bridge pattern has a wide range of application scenarios in actual development, especially in systems that need to support changes in multiple dimensions. The following are several typical application scenarios:

1. Cross-platform applications: When developing cross-platform applications, you can use the bridge pattern to decouple platform-related implementations from business logic. For example, the UI library can implement different rendering logic on different platforms, while the business logic can remain unchanged.

2. Database Operations：The bridge pattern can decouple the database operation interface from the specific database implementation. For example, business logic can access different databases (such as MySQL, PostgreSQL) through a common interface without knowing the specific implementation details.

3. Network transmission: When implementing a network transmission system, you can use the bridge mode to separate the data transmission protocol (such as HTTP, WebSocket) from the business logic, making the system more flexible.

Notes on using bridge mode

1. Increased design complexity：Although the bridge mode improves the flexibility of the system, it also increases the complexity of the design. When the system does not need multiple dimensions to change independently, there is no need to use the bridge mode.
2. Clear applicable scenarios：The bridge pattern is suitable for scenarios where multiple dimensions change independently. If the system only changes in one dimension, it may be simpler to use inheritance or composition directly.
3. Abstract interface design: The bridge pattern relies on the design of the interface, so it is necessary to ensure that the interface design is general enough to meet the needs of multiple implementation methods.

Bridge pattern vs inheritance

Summarize

The bridge pattern is a very useful design pattern that improves the flexibility and scalability of the system by separating the abstract part from the implementation part. In Golang, the implementation of the bridge pattern is relatively simple and can be achieved through the combination of interfaces and structures. The bridge pattern is particularly suitable for systems that handle multi-dimensional changes, such as cross-platform applications, database operations, and network transmission.

Reference Links

• Design Patterns - Bridge Pattern
• Go Design Patterns