Use Cases of Variable Templates in C++

Since C++14 variables can also be templatized. A variable template defines a family of variable (when declared at namespace scope) or a family of static data members (when defined at class scope). The question is, what is the benefit of variable templates?

The choice between typename and class

When working with C++ templates, you have probably seen typename and class used interchangeably. Is there a difference between them? This post will explain when these two keywords can be used in templates. Let’s consider the following example: In this context, when declaring a type template parameter, there is no difference, they are interchangeable. They…

When a type is not a type

Class template argument deduction is a useful feature in C++17 that helps developers to simplify the code by avoiding writing the template argument list when initializing objects of class templates (or when performing function-style casts). The compiler provides an implicit set of deduction guides, which are fictional function templates for a hypothetical class and uses them to perform template argument deduction and overload resolution. However, you can extend this set of deduction guides with your own, and in some cases, such as for aggregate types, you need to do so.

template <auto>

If you wanted to create templates with non-type template parameters, you had to specify both the type and the value. In C++17, this is no longer the case, as template <auto> helps simplify these scenarios.

Five examples for avoiding the preprocessor

The C++ preprocessor is a text replacement tool used to transform the source code in order to produce a single text file that is then passed to the actual compiler. It has various capabilities, such as including files, conditional compilation, text macro replacement, error emitting, stringizing, or token concatenation. Often developers use the preprocessor when other alternatives are available and are more appropriate. In this article, I will show five examples of when and how you can avoid the use of the preprocessor.

T4 Lessons Learned

Working with T4 recently I learned a couple of valuable lessons I’d like to share. Lesson 1: Template Language One of the parameters of the language directive is the language, which specifies the language used in the code blocks of the template. Two languages are specified, C# and VB. <#@ template language=”C#” #> However, any…