With the introduction of C++11, a developer now has the flexibility to invoke one constructor from another, offering a seamless way to consolidate constructor codes. Here’s how it looks when the second constructor is summoned within the initialization list of the initial one:
```cpp
class Fruit
{
public:
Fruit(const std::string& name, int number)
: name_(name), number_(number)
{}
Fruit(const std::string& name)
: Fruit(name, -1)
{}
private:
std::string name_;
int number_;
};
```In contrast, C++03 lacked this ability. Any attempts to incorporate a constructor call in the initialization list would result in a syntax blunder. Meanwhile, situating it inside the constructor body merely spawns a fleeting object:
```cpp
Fruit(const std::string& name)
{
Fruit(name, -1); // Regrettably, this only yields a transient object
}
```Yet, there’s a silver lining. Constructors can be amalgamated by leveraging default parameters:
```cpp
Fruit(const std::string& name, int number=-1)
: name_(name), number_(number)
{}
```Alternatively, a developer might opt for an Init() function to undertake the initialization, delegating this task to the constructors:
```cpp
Fruit(const std::string& name, int number)
{
Init(name, number);
}
Fruit(const std::string& name)
{
Init(name, -1);
}
void Init(const std::string& name, int number)
{
name_ = name;
number_ = number;
}
```However, the Init() method doesn’t come without its drawbacks:
- Fields undergo a default initialization during the constructor phase, only to be initialized once more in the Init() function;
- Base class constructors that require specific values cannot access values initialized in the Init() function due to the delay;
- Furthermore, this method falls short when it comes to initializing const pointers or reference members since they necessitate initialization within the initialization list.
To wrap up
In summarizing the evolution of constructor practices in C++, the introduction of C++11 significantly enhanced the flexibility and efficiency of code structuring. Prior to this, developers faced limitations in C++03, which prevented direct calls from one constructor to another. This was both restrictive and, at times, led to redundant code. C++11’s ability to delegate constructor functions streamlined code and reduced repetition. Yet, for those still working within the C++03 framework, alternative strategies like using default parameters or the Init() method are available. However, it’s worth noting that these methods, especially the Init() function, have inherent drawbacks. For instance, they can introduce redundancies in field initialization or pose challenges in initializing const pointers. The developments in C++11 underscore the language’s progression towards greater efficiency and intuitiveness. For developers, staying updated with these advancements not only elevates the quality of their code but also ensures they harness the full potential of the tools at their disposal. As programming languages continue to evolve, so does the need for programmers to adapt and grow, ensuring that best practices are consistently upheld.