Impara Generic Lambdas | Advanced Functional Patterns

Generic lambdas in C++ allow you to write functions that operate on any type without specifying the type explicitly. This is made possible by using auto in the lambda parameter list. When you write a lambda like [&](const auto& value) { /*...*/ }, the compiler generates a unique version of the lambda for each type it is called with, similar to how templates work.

Using auto as a parameter type in lambdas offers several benefits:

Reduces the need for boilerplate code by eliminating explicit type declarations;
Makes your code more flexible and reusable, as the same lambda can handle different types;
Enables you to write concise, type-agnostic utilities that work seamlessly across various contexts;
Helps you avoid errors that can arise from manual type specification.

This approach is especially useful in generic programming and when working with algorithms that accept callable objects. You can pass a generic lambda to std::for_each, std::transform, or any function that expects a callable, and the lambda will adapt to the element type automatically.

main.cpp


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#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

int main() {
    // Define a generic lambda that prints any type of value
    auto printValue = [](const auto& value) {
        std::cout << value << std::endl;
    };

    // Use with an int
    printValue(42);

    // Use with a double
    printValue(3.1415);

    // Use with a string
    printValue(std::string("Hello, world!"));

    // Use with a vector (prints address since vector does not overload operator<<)
    std::vector<int> numbers = {1, 2, 3};
    printValue(numbers.size());

    // Use with an element from the vector
    printValue(numbers[1]);

    // Use with a char
    printValue('A');

    return 0;
}

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Sezione 3. Capitolo 3

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Suggested prompts:

Can you show an example of a generic lambda in C++?

What are some limitations of using generic lambdas?

How do generic lambdas compare to function templates?

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Using auto as a parameter type in lambdas offers several benefits:

Reduces the need for boilerplate code by eliminating explicit type declarations;
Makes your code more flexible and reusable, as the same lambda can handle different types;
Enables you to write concise, type-agnostic utilities that work seamlessly across various contexts;
Helps you avoid errors that can arise from manual type specification.

main.cpp


              123456789101112131415161718192021222324252627282930313233
            
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

int main() {
    // Define a generic lambda that prints any type of value
    auto printValue = [](const auto& value) {
        std::cout << value << std::endl;
    };

    // Use with an int
    printValue(42);

    // Use with a double
    printValue(3.1415);

    // Use with a string
    printValue(std::string("Hello, world!"));

    // Use with a vector (prints address since vector does not overload operator<<)
    std::vector<int> numbers = {1, 2, 3};
    printValue(numbers.size());

    // Use with an element from the vector
    printValue(numbers[1]);

    // Use with a char
    printValue('A');

    return 0;
}

Tutto è chiaro?

Grazie per i tuoi commenti!

Sezione 3. Capitolo 3