Memory

Passing smart pointers is an important topic that is seldom addressed. This ends with the C++ core guidelines because they have six rules for passing std::shared_ptr and std::unique_ptr.

There were a lot of C++ experts who said that smart pointers were the most important feature of C++11. Today, I will write about smart pointers in C++.

The guidelines has six rules for explicit memory allocation and deallocation. Six! Maybe you are surprised because there is a simple rule in modern C++: don't use new and delete. Obviously, the story is not so simple.

This and the next posts will probably be about the most important concern in programming: resource management. The C++ Core Guidelines have rules for resource management in general but also rules for allocation and deallocation and smart pointers in particular. Today I will begin with the general rules of resource management.

After I have written a few posts about memory management in C++, I'm very glad to present Jonathan Müller, which will write a guest post about his implementation of the memory library. He will explain to us his concepts about his design. Jonathan is known as an expert in memory management in the C++ community. In the  59 episodes, he presented his ideas to a worldwide audience.

In C++ you have the choice between various memory allocation strategies. In addition to the frequently used dynamic memory allocation, you have the stack allocation. But you can preallocate the memory at the start time of your program. This can be a fixed-sized block or one or more memory pools. Each of these strategies has its pros and cons. Which one, I will answer in this post.

There a lot of different strategies for allocating memory. Programming languages like Python or Java request their memory from the heap at runtime. Of course, C or C++ has also a heap but prefers the stack. But these are by far not so only strategies for allocating memory. You can preallocate memory at the start time of the program as a fixed block or as a pool of memory blocks. This preallocated memory can afterward be used at the runtime of your program. But the key question is: What are the pros and cons of the various strategies to allocate memory?

What is common between all containers of the Standard Template Library? They have a type parameter Allocator that is by default std::allocator. The job of the allocator is to manage the lifetime of its elements. That means to allocate and deallocate memory for its elements and to initialize and destruct them.

In my post Time for Wishes, I asked: "How can I improved my blog?" And here are the answers.

I overloaded in the last post operator new and delete. Therefore, it was possible to find memory leaks and get a first hint of the bad guys. My solution had two not so nice properties. With this post, I will overcome them.