{"id":1917,"date":"2021-04-01T00:51:56","date_gmt":"2021-04-01T04:51:56","guid":{"rendered":"https:\/\/blog.wholetomato.com\/?p=1917"},"modified":"2023-11-21T06:39:33","modified_gmt":"2023-11-21T10:39:33","slug":"how-to-modernize-with-visual-assist-part-2","status":"publish","type":"post","link":"https:\/\/www.wholetomato.com\/blog\/how-to-modernize-with-visual-assist-part-2\/","title":{"rendered":"How To Modernize With Visual Assist Part 2"},"content":{"rendered":"\r\n

In the previous article, you read about five popular techniques to improve your projects and apply several Modern C++ patterns. Here’s a list of five more things! We’ll go from the override keyword to nullptr, scoped enums, and more. All techniques are super-easy with Visual Assist!<\/p>\r\n\r\n

1. Override<\/span><\/strong><\/span><\/h2>\r\n

Let’s have a look at the following code with a simple class hierarchy:<\/p>\r\n\r\n

using BmpData = std::vector<int>;\r\n\r\nclass BaseBrush {\r\npublic:\r\nvirtual ~BaseBrush() = default;\r\n\r\nvirtual bool Generate() = 0;\r\n\r\nvirtual BmpData ApplyFilter(const std::string&) { return BmpData{}; }\r\n};\r\n\r\nclass PBrush : public BaseBrush {\r\npublic:\r\nPBrush() = default;\r\n\r\nbool Generate() { return true; }\r\n\r\nBmpData ApplyFilter(const std::string& filterName) {\r\nstd::cout << \"applying filter: \" << filterName;\r\nreturn BmpData{};\r\n}\r\n\r\nprivate:\r\nBmpData m_data;\r\n};<\/pre>\r\n\r\n\r\n\r\n
When you run VA code inspections, you’ll immediately see that it complains about not using the override keyword on those two virtual methods.<\/p>\r\n\r\n
\"image1\"<\/p>\r\n
In short, the override keyword allows us to explicitly specify that a given member function overrides a function from a base class. It’s a new keyword available since C++11.<\/p>\r\n
As you might already know, you can go to VA Code Inspection<\/a> Results and apply the fixes automatically. You’ll get the following code:<\/p>\r\n\r\n
class PBrush : public BaseBrush {\r\npublic:\r\nPBrush() = default;\r\n\r\nbool Generate() override;\r\n\r\nBmpData ApplyFilter(const std::string& filterName) override;\r\nprivate:\r\nBmpData m_data;\r\n};<\/pre>\r\n\r\n\r\n\r\n
What are the benefits of using override?<\/p>\r\n\r\n\r\n\r\n
The most significant advantage is that we can now easily catch mismatches between the virtual base function and its override. When you have even a slight difference in the declaration, then the virtual polymorphism will <\/em>might<\/s> not work.\u00a0<\/p>\r\n\r\n\r\n\r\n
Another critical point is code expressiveness. With override, it’s effortless to read what the function is supposed to do.<\/p>\r\n\r\n\r\n\r\n
And another one is being more modern as this keyword is also available in other languages like C#, Visual Basic, Java, and Delphi.<\/p>\r\n\r\n\r\n\r\n
2. <\/strong>nullptr<\/strong><\/h2>\r\n\r\n\r\n\r\n
When I work with legacy code, my Visual Assist Code Inspection Result is often filled with lots of the following items:<\/p>\r\n\r\n
\"image3\"<\/p>\r\n
This often happens with code like:<\/span><\/p>\r\n\r\n
if (pInput == NULL) {\r\n    LOG(Error, \"input is null!\")\r\n    return;\r\n}<\/pre>\r\n\r\n\r\n\r\n
or<\/p>\r\n\r\n\r\n\r\n
pObject->Generate(\"image.bmp\", NULL, NULL, 32);<\/pre>\r\n\r\n\r\n\r\n
Why does Visual Assist complain about the code? It’s because NULL is just a define and means only 0, so it doesn’t mean a null pointer, but it means 0. This is also a problem when you have code like:<\/p>\r\n\r\n\r\n\r\n
int func(int param);\r\nint func(float* data);\r\nif you call:\r\nfunc(NULL);\r\n<\/pre>\r\n\r\n\r\n\r\n
You could expect that the function with the pointer should be called, but it’s not. That’s why it’s often a guideline in C or early C++ that suggests not making function overrides with pointers and integral types.<\/p>\r\n\r\n\r\n\r\n
The solution? Just use nullptr from C++11.<\/p>\r\n\r\n\r\n\r\n
nullptr is not 0, but it has a distinct type nullptr_t.<\/p>\r\n\r\n\r\n\r\n
Now when you write:<\/p>\r\n\r\n\r\n\r\n
func(nullptr);<\/pre>\r\n\r\n\r\n\r\n
you can expect the proper function invocation. The version with func(float* data) will be invoked.<\/p>\r\n\r\n\r\n\r\n
Not to mention that nullptr is a separate keyword in C++, so it stands out from the regular code. Sometimes NULL is displayed in a different color, but sometimes it is not.<\/p>\r\n\r\n\r\n\r\n
Visual Assist makes it super easy to apply the fix, and it’s a very safe change.<\/p>\r\n\r\n\r\n\r\n
3. Convert <\/strong>enum<\/strong> to scoped <\/strong>enum<\/strong><\/h2>\r\n\r\n\r\n\r\n
Another pattern that is enhanced with Modern C++ is a way you can define enums.<\/p>\r\n\r\n\r\n\r\n
It was popular to write the following code:<\/p>\r\n\r\n\r\n\r\n
enum ActionType {\r\n    atNone,\r\n    atProcess,\r\n    atRemove,\r\n    atAdd\r\n};\r\n\r\nActionType action = atNone;\r\nSince C++11 it's better to you can define this type in the following way:\r\nenum class ActionType {\r\n    None,\r\n    Process,\r\n    Remove,\r\n    Add\r\n};\r\n\r\nActionType action = ActionType::None;<\/pre>\r\n\r\n\r\n\r\n
What are the benefits of such transformations?<\/p>\r\n\r\n\r\n\r\n