[c++] Generalized lambda capture

11 Dec 2023

In C++, lambda functions are a powerful feature for creating anonymous functions within the scope of the function they are used in. Prior to C++14, lambda functions were limited in their ability to capture variables from their enclosing scope, particularly when it came to capturing by move semantics or capturing this by value. However, with the introduction of generalized lambda capture in C++14, these limitations were overcome.

1. Introduction to Lambda Capture

In C++ lambda functions, variables from the enclosing scope can be captured by value [=] or by reference [&] using the capture list. However, capturing by move semantics or capturing this by value used to be problematic prior to C++14.

2. Generalized Lambda Capture in C++14

C++14 introduced the ability to capture variables by move semantics and capture this by value in lambda functions. This is achieved by specifying the variable to be captured within square brackets and using the move capture syntax name = std::move(varName) for move capture, and this for capturing this by value.

Example:

// Generalized Lambda Capture in C++14
auto func = [name = std::move(varName), this](){ /* lambda body */ };

In the above example, name is captured by move semantics and this is captured by value within the lambda function.

3. Benefits of Generalized Lambda Capture

Generalized lambda capture in C++14 provides more flexibility and expressiveness when working with lambda functions. It allows for capturing variables by move semantics, capturing this by value, and capturing multiple variables with different capture types in a single lambda function.

4. Conclusion

With the introduction of generalized lambda capture in C++14, lambda functions in C++ became more powerful and versatile, expanding their capabilities in capturing variables from the enclosing scope. This feature provides additional flexibility and expressiveness when using lambda functions in C++.

References

C++ Reference: Lambda expressions
Bjarne Stroustrup, “The C++ Programming Language, 4th Edition”

위치 => sample/coding/c++