Скачать или смотреть Automatically Register Class Members in C+ + : A Design Strategy

Discover a robust solution to automatically register class member changes in C+ + . Learn the techniques to avoid errors during class evolution in C+ + .
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Automatically Register Class Members in C+ + : A Design Strategy

When designing software in C+ + , managing the state of class members is crucial—especially when changes occur over time. One common scenario arises when you have a series of class members that need to be persistently stored in a database or an external file upon certain conditions, such as when they change. The challenge lies in ensuring that any new members added to a class are automatically recognized and handled correctly, without the risk of human error.

In this guide, we’ll explore a robust design pattern that allows class members to be automatically registered and monitored for changes, ultimately simplifying the implementation of persistent data storage. We’ll break down the solution into clear sections to help you integrate these principles into your own C+ + projects.

Understanding the Problem

Consider a class called MyRow, which contains multiple MyCell objects. Each MyCell holds data and has a mechanism to determine whether its contents have been modified (marked as "dirty"). When MyRow is about to be destroyed, it should verify whether any of its MyCell members have changed, so it can persist the data to a database if necessary.

The typical approach involves explicitly iterating over each MyCell in a method—like IsDirty()—to check whether any of them require action. However, this can lead to errors, particularly if developers forget to include new MyCell variables in this check.

The Solution: Leveraging C+ + Features

To circumvent the pitfalls of manual registration, the proposed solution involves using template metaprogramming and C+ + features like tuples and integer sequences. Below are the key components:

Step 1: Define the Cell Structure

First, we need to define a generic cell structure:

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Step 2: Create a Tuple for MyCells

Next, we create a tuple structure to hold our cells. This helps manage multiple MyCell instances without manual iteration:

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Step 3: Row Class Implementation

We define a Row class that will be responsible for managing these cells:

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Step 4: Defining Rows and Types

Now, for each row (like MyRow), we need to define a cells structure that specifies both the types and names of MyCell instances:

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Step 5: Main Function Implementation

Finally, we can put the MyRow class into action, using it to obtain and manipulate cell values.

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Conclusion

This design strategy reduces the boilerplate code required to maintain the integrity of class member changes in C+ + . By utilizing C+ + templates and tuples, we ensure that every member addition is automatically recognized and handled appropriately.

Implementing this pattern may introduce some initial complexity due to its boilerplate nature, but it pays off in enhancing robustness and minimizing human error. With a bit of practice, adapting this method will lead to more reliable, maintainable C+ + code that handles class member changes seamlessly.



By following this structured approach, you're equipped to improve your design strategies when working with classes in C+ + , ensuring that your applications are both efficient and error-free.