How Can Constructor Delegation Streamline Initialization in C ?

Delegating Constructors in C : A Comprehensive Guide

When dealing with multiple constructors that share similar functionality, it becomes necessary to delegate construction to streamline the initialization process. While the syntactic sugar introduced in C x11 simplifies this task, it's crucial to understand the nuances.

Constructor Delegation Syntax

The correct approach to delegate constructors in C involves using the constructor's initialization list. Refer to the following example:

class Bitmap {
public:
    Bitmap(HBITMAP Bmp) {
        // Construct bitmap
    }

    Bitmap(WORD ResourceID) : Bitmap((HBITMAP)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(ResourceID), IMAGE_BITMAP, 0, 0, LR_SHARED)) {
    }
};

In this example, the Bitmap(WORD ResourceID) constructor initializes the bitmap by delegating to the Bitmap(HBITMAP) constructor using the initialization list. This avoids creating unnecessary temporary objects or introducing errors.

Incorrect Approach

The alternative syntax you presented, using a function body to call the other constructor, is incorrect. This will result in creating a temporary object instead of delegating construction.

Bitmap::Bitmap(WORD ResourceID) {
    HBITMAP BMP = (HBITMAP)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(ResourceID), IMAGE_BITMAP, 0, 0, LR_SHARED);
    Bitmap(BMP); // Incorrect, creates a temporary
}

Conclusion

To effectively delegate constructors in C , it is imperative to utilize the constructor's initialization list. By leveraging this technique, you can avoid unnecessary object creation and ensure code efficiency and maintainability.

The above is the detailed content of How Can Constructor Delegation Streamline Initialization in C ?. For more information, please follow other related articles on the PHP Chinese website!