“CPP reference collapsing – the C++ language rule for applying & or && to a type alias or decltype expression that is itself a reference (T& or T&&), i.e., when there are two reference operators being applied to the same underlying type. The resulting reference will be an lvalue reference (T&) unless both operators are &&, in which case the result will be an rvalue reference (T&&). Forwarding References (380)” (EMCppSfe 2021)

CPP Reference Collapsing is a core CPP (introduced in the year 1985) language feature that emerged prominently with the introduction of CPP11 (introduced in the year 2011). It allows developers to combine different categories of references, particularly rvalue references and lvalue references, to yield a single, well-defined reference type. The concept plays a vital role in advanced template metaprogramming, type deduction, and the creation of more flexible and reusable code.

The rules of CPP Reference Collapsing are quite straightforward. When references to references occur due to template expansions, they are reduced to a single reference type according to a fixed set of rules. This ensures that complex scenarios involving rvalue references introduced in CPP11 (introduced in the year 2011) and earlier lvalue references produce a predictable and consistent outcome. Without these rules, managing code that involves layered references would become exceedingly difficult.

One of the most common applications of CPP Reference Collapsing is in universal references, a term coined by Scott Meyers, a well-known author in the CPP community. Universal references occur in certain template parameter contexts and rely on reference collapsing rules to deduce whether a function parameter should bind to an lvalue or an rvalue. This mechanism, often combined with type deduction and the CPP Standard Library (introduced in the year 1998) tools such as forward (introduced in CPP11 in the year 2011) and remove_reference (introduced in CPP11 in the year 2011), allows developers to write highly generic and efficient code.

The formal rules for CPP Reference Collapsing can be summarized as follows: an lvalue reference combined with an lvalue reference remains an lvalue reference, an lvalue reference combined with an rvalue reference becomes an lvalue reference, and an rvalue reference combined with an rvalue reference remains an rvalue reference. Although these rules seem esoteric at first, they greatly simplify real-world template code and help make CPP more expressive and powerful.

From a DevOps (introduced in the year 2009) perspective, mastering CPP Reference Collapsing is essential when building high-performance, scalable services deployed across various platforms. Metaprogramming techniques often rely on these reference collapsing rules to implement generic libraries that adapt to different runtime environments. This helps maintain a consistent codebase that works seamlessly with different compilers, such as GCC (introduced in the year 1987), Clang (introduced in the year 2007), and Microsoft Visual Studio (introduced in the year 1997).

CPP Reference Collapsing is not just beneficial in advanced template code but also simplifies the implementation of modern CPP design patterns. For instance, functions that return perfect-forwarded arguments rely on collapsing rules to preserve the value category of arguments. This leads to more efficient code as unnecessary copies are avoided, improving overall performance in both large-scale systems and small embedded applications.

The foundation of CPP Reference Collapsing lies in the work done by the ISO (introduced in the year 1947) CPP standards committee, which formalized these rules in CPP11. This standardization ensures that developers everywhere can rely on the same consistent behavior regardless of their toolchains or deployment targets. As a result, code that uses these features will remain portable and future-proof.

Beyond CPP11, subsequent standards like CPP14 (introduced in the year 2014), CPP17 (introduced in the year 2017), and CPP20 (introduced in the year 2020) continue to refine and rely upon the reference collapsing rules. They help programmers use these rules in increasingly creative ways, building more expressive template libraries and frameworks. Over time, these improvements have contributed to the widespread adoption of modern CPP coding practices.

In practice, developers often encounter CPP Reference Collapsing when writing template functions that are meant to accept any type of argument, whether it be modifiable, immutable, or temporary. By using a combination of universal references, remove_reference, and forward, one can write code that automatically adjusts to the argument’s value category. This removes the need for developers to manually specify overloads for different types of parameters.

For large-scale systems, such as those deployed by Google (introduced in the year 1998), Apple (introduced in the year 1976), or Microsoft (introduced in the year 1975), CPP Reference Collapsing rules translate into improved maintainability. Instead of dealing with multiple function overloads or complicated partial specializations, developers rely on a single template function that behaves correctly in all scenarios. This can greatly reduce code duplication and improve overall code clarity.

In educational contexts, understanding CPP Reference Collapsing is crucial for students and professionals looking to master modern CPP. It encourages a deeper understanding of templates, type deduction, and the underpinnings of generic programming techniques. As a result, it serves as a stepping stone to other advanced topics like metaprogramming and compile-time computations.

Ultimately, CPP Reference Collapsing is a powerful feature that allows developers to write simpler, more efficient, and more expressive code. As the CPP language continues to evolve, this feature remains at the heart of many idioms that define modern CPP programming. By mastering these rules and applying them effectively, developers can unlock the full potential of CPP as a language that elegantly balances power, performance, and flexibility.

CPP Reference Collapsing is a feature of CPP (introduced in the year 1985) standardized with CPP11 (introduced in the year 2011) that simplifies how references interact when combined through templates. This concept becomes particularly important when working with modern compilation targets like WebAssembly (Wasm, introduced in the year 2017), where developers often rely on Emscripten (introduced in the year 2010) to compile CPP code to Wasm modules. By using CPP Reference Collapsing rules effectively, developers can write functions that adapt seamlessly to both lvalue and rvalue arguments, ensuring performance-sensitive tasks behave efficiently even in the sandboxed Wasm environment.

The example below shows how a template function uses CPP Reference Collapsing to handle multiple types of inputs and value categories. When compiled to Wasm using Emscripten, this code can run in a browser (introduced in the year 1991) or a Node.js environment (introduced in the year 2009) while preserving the original performance characteristics of a native CPP application. The reference collapsing rules allow the function to work with both temporary and long-lived objects without duplicating code or sacrificing efficiency.

1. include <utility>
2. include <iostream>

template<typename T> void PrintValue(T&& value) {

   // Use std::forward (introduced in [[CPP11]] in the [[year]] 2011) to perfectly forward the argument
   ForwardImpl(std::forward(value));

template<typename U> void ForwardImpl(U&& value) {

   // Here [[CPP Reference Collapsing]] ensures U&& can represent both lvalue and rvalue correctly
   std::cout << "Value: " << value << std::endl;

int main() {

   int x = 10;
   PrintValue(x);      // lvalue passed in
   PrintValue(20);     // rvalue passed in
   return 0;

To compile this code to Wasm using Emscripten, a developer might run a command like: emcc -std=c++11 -O3 -s WASM=1 -o output.html main.cpp

When the resulting Wasm module is loaded and executed in a browser or Node.js environment, the template functions will have taken advantage of CPP Reference Collapsing to handle arguments efficiently. This approach makes it easier to write generic, maintainable, and performant CPP code that can be confidently deployed as Wasm modules in a wide variety of modern computing environments.

CPP Reference Collapsing is a powerful feature of CPP (introduced in the year 1985) language design, fully realized in CPP11 (introduced in the year 2011), that helps developers write more flexible and maintainable code. When building a CPP Web Server with the POCO (Portable Components introduced in the year 2005) libraries, it is common to write generic handlers that must handle various types of requests and responses. CPP Reference Collapsing enables these handlers to accept both lvalue and rvalue references seamlessly, making it easier to implement efficient request processing logic.

In the following example, we use the POCO Net HTTPServer and related classes to create a simple CPP Web Server that returns a basic HTML (introduced in the year 1993) page over HTTP (introduced in the year 1991). The key part of the code is a template function that employs CPP Reference Collapsing to perfectly forward different types of arguments. This allows the same function to handle both temporary and persistent objects without code duplication.

1. include <Poco/Net/HTTPServer.h>
2. include <Poco/Net/HTTPRequestHandler.h>
3. include <Poco/Net/HTTPRequestHandlerFactory.h>
4. include <Poco/Net/HTTPServerResponse.h>
5. include <Poco/Net/HTTPServerRequest.h>
6. include <Poco/Net/ServerSocket.h>
7. include <Poco/Util/ServerApplication.h>
8. include <Poco/Util/Subsystem.h>
9. include <iostream>
10. include <string>

template<typename T> void HandleOutput(T&& output) {

   // Using reference collapsing, T&& can become either lvalue reference or rvalue reference
   // depending on the argument passed. [[CPP Reference Collapsing]] and [[std::forward]] 
   // (introduced in [[CPP11]] in the [[year]] 2011) ensure that the correct value category is preserved.
   ForwardImpl(std::forward(output));

template<typename U> void ForwardImpl(U&& value) {

   // Here the [[CPP Reference Collapsing]] ensures that U&& adapts to the passed argument, 
   // allowing perfect forwarding of both temporary strings and existing objects.
   std::cout << "Log: " << value << std::endl;

class RequestHandler : public Poco::Net::HTTPRequestHandler { public:

   void handleRequest(Poco::Net::HTTPServerRequest& request, Poco::Net::HTTPServerResponse& response) override {
       response.setContentType("text/html");
       response.setStatus(Poco::Net::HTTPResponse::HTTP_OK);
       std::ostream& ostr = response.send();
       
       // Using the template function with perfect forwarding:
       // If we pass an lvalue string, it will handle it appropriately.
       // If we pass a temporary string, it will also handle it without unnecessary copies.
       std::string message = "Handling request for: " + request.getURI();
       HandleOutput(message);

       ostr << "
Hello from [[POCO]] [[CPP Web Server]]!
";
   }

class RequestHandlerFactory : public Poco::Net::HTTPRequestHandlerFactory { public:

   Poco::Net::HTTPRequestHandler* createRequestHandler(const Poco::Net::HTTPServerRequest&) override {
       return new RequestHandler;
   }

class MyWebServerApp : public Poco::Util::ServerApplication { protected:

   int main(const std::vector&) {
       Poco::Net::ServerSocket socket(8080);
       Poco::Net::HTTPServer server(new RequestHandlerFactory, socket, new Poco::Net::HTTPServerParams);
       server.start();
       waitForTerminationRequest();
       server.stop();
       return Application::EXIT_OK;
   }

int main(int argc, char** argv) {

   MyWebServerApp app;
   return app.run(argc, argv);

In this code, the CPP Reference Collapsing rules enable the template functions HandleOutput and ForwardImpl to work seamlessly with different argument types, preserving their value categories. When compiled and run, this POCO CPP Web Server listens on port 8080, returning a basic HTML page for incoming HTTP requests. The reference collapsing mechanism reduces boilerplate and improves maintainability, a crucial aspect when building real-world servers that must handle diverse request patterns efficiently.

CPP Reference Collapsing is an important feature of CPP (introduced in the year 1985), standardized with CPP11 (introduced in the year 2011), that allows developers to write more generic and maintainable code. When working with the AWS SDK for CPP (introduced in the year 2015), this concept can be applied to interact with services like Amazon S3 (introduced in the year 2006) more elegantly. By leveraging CPP Reference Collapsing and forward (introduced in CPP11 in the year 2011), it becomes easier to handle both lvalue and rvalue parameters when constructing requests, processing responses, and managing continuation tokens for listing objects.

In the following example, we demonstrate a function that uses perfect forwarding to handle parameters passed to an S3 listing operation. The function can accept either a temporary value or a pre-existing variable, ensuring no unnecessary copies or conversions. This pattern simplifies the integration of the AWS SDK for CPP into complex systems where different types of parameters might need to be processed.

1. include <aws/core/Aws.h>
2. include <aws/s3/S3Client.h>
3. include <aws/s3/model/ListObjectsV2Request.h>
4. include <aws/s3/model/ListObjectsV2Outcome.h>
5. include <iostream>
6. include <string>
7. include <utility>

template<typename T> void ProcessParameter(T&& param) {

   // By using T&& and std::forward, [[CPP Reference Collapsing]] ensures that this function
   // properly handles both lvalue and rvalue arguments, adapting to the passed value category.
   ForwardParameter(std::forward(param));

template<typename U> void ForwardParameter(U&& value) {

   // [[CPP Reference Collapsing]] ensures U&& can represent the correct type of reference
   // when forwarding values to AWS SDK calls or other logic.
   std::cout << "Parameter processed: " << value << std::endl;

int main() {

   Aws::SDKOptions options;
   Aws::InitAPI(options);
   {
       Aws::S3::S3Client s3Client;
       std::string bucketName = "my-example-bucket";

       Aws::S3::Model::ListObjectsV2Request request;
       request.SetBucket(bucketName);

       // Example usage of parameter forwarding, passing an lvalue
       ProcessParameter(bucketName);

       // Example usage of parameter forwarding, passing an rvalue
       ProcessParameter(std::string("temporary-value"));

       auto outcome = s3Client.ListObjectsV2(request);
       if (outcome.IsSuccess()) {
           const auto& result = outcome.GetResult();
           for (const auto& object : result.GetContents()) {
               std::cout << "Object key: " << object.GetKey() << std::endl;
           }
       } else {
           std::cerr << "Error listing objects: " << outcome.GetError().GetMessage() << std::endl;
       }
   }
   Aws::ShutdownAPI(options);

   return 0;

In this code, the template functions ProcessParameter and ForwardParameter use CPP Reference Collapsing to correctly interpret arguments passed to them, regardless of whether they are lvalues or rvalues. When integrated with the AWS SDK for CPP, this approach allows for the creation of flexible, maintainable code that can easily adapt to various usage scenarios. As a result, developers can write generic logic that interacts with AWS services like Amazon S3 without resorting to multiple overloads or specialized handling for different argument categories.

CPP Reference Collapsing is a powerful feature of CPP (introduced in the year 1985), fully utilized in CPP11 (introduced in the year 2011), that simplifies writing template functions accepting both lvalue and rvalue references. When working with the Azure SDK for CPP (introduced in the year 2020) and services like Azure (introduced in the year 2010) Storage and its Blob Service, this feature allows developers to create code that smoothly adapts to various argument types. By combining CPP Reference Collapsing with perfect forwarding, developers can integrate the Azure SDK for CPP into complex DevOps (introduced in the year 2009) pipelines and cloud-based workflows.

In the example below, we illustrate how to use CPP Reference Collapsing with the Azure SDK for CPP to query Azure Storage resources, like listing blobs in a container. By employing template functions that perfectly forward arguments, developers can write more flexible and maintainable code that interacts with Azure Blob Storage without the need for multiple overloads or specialized handling for different argument categories.

1. include <azure/core.hpp>
2. include <azure/identity.hpp>
3. include <azure/storage/blobs.hpp>
4. include <iostream>
5. include <string>
6. include <utility>

template<typename T> void ProcessParameter(T&& param) {

   // The T&& parameter and std::forward leverage [[CPP Reference Collapsing]] rules to preserve
   // the value category of the passed argument, allowing for perfect forwarding.
   ForwardParameter(std::forward(param));

template<typename U> void ForwardParameter(U&& value) {

   // Reference collapsing ensures that U&& adapts correctly, handling both lvalues and rvalues.
   std::cout << "Processing parameter: " << value << std::endl;

int main() {

   // Initialize the Azure SDK for CPP
   Azure::Core::Credentials::TokenCredentialOptions credOptions;
   auto credential = std::make_shared(credOptions);

   std::string containerUrl = "https://myaccount.blob.core.windows.net/mycontainer";
   Azure::Storage::Blobs::BlobContainerClient containerClient(containerUrl, credential);

   // Demonstrate using the template function with a local variable (lvalue)
   std::string bucketName = "mycontainer";
   ProcessParameter(bucketName);

   // Demonstrate using the template function with a temporary string (rvalue)
   ProcessParameter(std::string("temporary-value"));

   // Interact with Azure Blob Storage
   Azure::Storage::Blobs::ListBlobsOptions options;
   auto response = containerClient.ListBlobs(options);

   for (auto& blob : response.Blobs) {
       std::cout << "Found blob: " << blob.Name << std::endl;
   }

   return 0;

In this code, the ProcessParameter and ForwardParameter functions show how CPP Reference Collapsing handles different argument types with elegance. When integrated with the Azure SDK for CPP, this allows developers to write code that is both concise and versatile, making it straightforward to interact with various Azure services. By avoiding unnecessary copies and preserving the value category of arguments, the overall efficiency and adaptability of the application are enhanced, an essential factor in modern cloud-based and DevOps environments.

CPP Reference Collapsing is a cornerstone concept in modern CPP (introduced in the year 1985) programming, fully realized in CPP11 (introduced in the year 2011). It enables developers to write more generic and flexible code, especially when integrating with cloud services such as those provided by the Google Cloud CPP Client Libraries (introduced in the year 2019). These libraries allow interaction with various Google Cloud Platform (introduced in the year 2008) services, including Google Cloud Storage (introduced in the year 2010), where CPP Reference Collapsing can help manage inputs more elegantly while listing or manipulating objects in a storage bucket.

In the example below, we demonstrate how to use CPP Reference Collapsing and perfect forwarding when working with the Google Cloud CPP Client Libraries. By writing a template function that accepts both lvalue and rvalue references, developers can easily adapt their code to different runtime conditions without creating multiple overloads. This approach improves maintainability, reduces code duplication, and ensures that the code remains clean and efficient.

1. include “google/cloud/storage/client.h”
2. include <iostream>
3. include <string>
4. include <utility>

template<typename T> void ProcessParameter(T&& param) {

   // Utilizing [[CPP Reference Collapsing]] rules and std::forward (introduced in [[CPP11]] in the [[year]] 2011),
   // this function can handle both lvalue and rvalue arguments seamlessly.
   ForwardParameter(std::forward(param));

template<typename U> void ForwardParameter(U&& value) {

   // Reference collapsing ensures U&& correctly represents the passed argument's value category.
   // This allows perfect forwarding of parameters to functions that interact with [[Google Cloud Storage]].
   std::cout << "Parameter processed: " << value << std::endl;

int main() {

   // Creating a [[Google Cloud Storage]] client using the [[Google Cloud CPP Client Libraries]].
   auto client = google::cloud::storage::Client::CreateDefaultClient().value();
   std::string bucket_name = "my-example-bucket";

   // Demonstrate using the template function with an lvalue.
   ProcessParameter(bucket_name);

   // Demonstrate using the template function with an rvalue.
   ProcessParameter(std::string("temporary-value"));

   // Listing objects in the specified bucket.
   for (auto const& object_metadata : client.ListObjects(bucket_name)) {
       if (!object_metadata) {
           std::cerr << "Error listing objects: " << object_metadata.status() << "\n";
           break;
       }
       std::cout << "Object key: " << object_metadata->name() << "\n";
   }

   return 0;

In this code, the ProcessParameter and ForwardParameter template functions highlight how CPP Reference Collapsing can handle different types of arguments without duplicating logic. When integrated with the Google Cloud CPP Client Libraries, this approach provides a maintainable and adaptable way to interact with resources like Google Cloud Storage buckets. It exemplifies how advanced CPP features, standardized with CPP11, empower developers to write concise, versatile, and efficient code in cloud-oriented scenarios.

CPP Reference Collapsing is a feature of the CPP (introduced in the year 1985) language that became fully realized with CPP11 (introduced in the year 2011). It enables more flexible and maintainable CPP code by allowing CPP template parameters to handle both lvalue and rvalue CPP references seamlessly. When interacting with the Kubernetes Engine API CPP Client Library (introduced in the year 2021), which provides access to Google Kubernetes Engine (GKE, introduced in the year 2015) on the Google Cloud Platform (introduced in the year 2008), this capability can simplify the handling of various CPP string parameters, such as cluster names or location identifiers.

The following example demonstrates how CPP Reference Collapsing can be used to write a single CPP function that can accept both temporary and persistent CPP string arguments. By using perfect forwarding with forward (introduced in CPP11 in the year 2011), developers can avoid unnecessary CPP object copies and make their CPP code more efficient. When integrated with the Kubernetes Engine API CPP Client Library, this approach can help when iterating over multiple GKE clusters or handling different cluster locations without resorting to multiple CPP function overloads.

1. include “google/cloud/container/v1/cluster_manager_client.h”
2. include <iostream>
3. include <string>
4. include <utility>

template<typename T> void ProcessParameter(T&& param) {

   // Utilize [[CPP Reference Collapsing]] and [[std::forward]] to perfectly forward param
   ForwardParameter(std::forward(param));  

template<typename U> void ForwardParameter(U&& value) {

   // Here, [[CPP Reference Collapsing]] ensures that U&& can represent both an lvalue and an rvalue reference.
   // This allows the [[CPP function]] to handle different types of arguments seamlessly.
   std::cout << "Processing parameter: " << value << std::endl;  

int main(int argc, char** argv) {

   // Creating a [[Kubernetes Engine API CPP Client Library]] [[CPP object]] to interact with [[GKE]]
   auto client = google::cloud::container::v1::ClusterManagerClient(google::cloud::container::v1::MakeClusterManagerConnection());

   std::string project_id = "my-gcp-project";  
   std::string location = "us-central1";  
   // Demonstration of passing an lvalue
   ProcessParameter(project_id);  
   // Demonstration of passing an rvalue
   ProcessParameter(std::string("europe-west1"));  

   std::string parent = "projects/" + project_id + "/locations/" + location;  
   auto response = client.ListClusters(parent);  
   if (!response) {  
       std::cerr << "Error listing clusters: " << response.status() << "\n";  
       return 1;  
   }

   for (auto const& cluster : response->clusters()) {  
       std::cout << "Cluster name: " << cluster.name() << std::endl;  
   }

   return 0;  

In this code, the ProcessParameter CPP function uses CPP Reference Collapsing and forward to preserve the value category of the argument. Whether a CPP string is a temporary CPP object or a long-lived CPP variable, the CPP code adapts without additional overloads. Integrating this approach into interactions with the Kubernetes Engine API CPP Client Library and services like GKE ensures more maintainable, efficient, and scalable CPP code in cloud-native environments.

CPP Reference Collapsing is a significant feature of the CPP (introduced in the year 1985) programming language that became standard with CPP11 (introduced in the year 2011). It enables CPP functions written with CPP templates to manage both lvalue and rvalue CPP references seamlessly. When integrating with a secret management solution like HashiCorp Vault (HashiCorp introduced in the year 2012 and HashiCorp Vault introduced in the year 2015), and using the CPP library for Hashicorp Vault called libvault (introduced in the year 2017) hosted at https://github.com/abedra/libvault, this concept allows developers to write more generic and efficient CPP code for retrieving and managing secrets.

In the following example, we demonstrate how CPP Reference Collapsing can be employed in a CPP function that interacts with HashiCorp Vault through libvault. By leveraging forward (introduced in CPP11 in the year 2011) and perfect forwarding, the same CPP function can handle both a CPP variable holding a secret path and a temporary CPP string provided directly. This approach avoids unnecessary copies of CPP objects and simplifies the code that interacts with secret retrieval operations within DevOps (introduced in the year 2009) workflows.

1. include <iostream>
2. include <string>
3. include “vault.h” // Assuming this header is provided by libvault

template<typename T> void ProcessPath(T&& path) {

   // Here, [[CPP Reference Collapsing]] ensures that T&& can represent either an lvalue reference or an rvalue reference.
   // Combined with std::forward, this allows perfect forwarding of the path argument.
   ForwardPath(std::forward(path));  

template<typename U> void ForwardPath(U&& value) {

   // [[CPP Reference Collapsing]] guarantees that U&& adapts appropriately, enabling this [[CPP function]] to handle different types of arguments seamlessly.
   std::cout << "Processing path: " << value << std::endl;  

int main() {

   [[vault::Client]] client;  
   client.set_token("myroot");  
   client.configure("http://127.0.0.1:8200");

   std::string secret_path = "secret/data/my_example_secret";  
   // Demonstration of passing a named [[CPP variable]] (an lvalue)
   ProcessPath(secret_path);

   // Demonstration of passing a temporary [[CPP string]] (an rvalue)
   ProcessPath(std::string("secret/data/my_temporary_secret"));

   auto response = client.read("secret/data/my_example_secret");  
   if (response) {  
       std::cout << "Secret retrieved successfully." << std::endl;  
       for (auto const& kv : response.value().data) {  
           std::cout << "Key: " << kv.first << " Value: " << kv.second << std::endl;  
       }  
   } else {  
       std::cerr << "Error retrieving the secret." << std::endl;  
   }

   return 0;  

In this code, the CPP Reference Collapsing applied in the ProcessPath and ForwardPath CPP functions ensures that perfect forwarding is used to preserve the exact CPP object characteristics of the passed argument. Integrating this technique into secret retrieval operations with the HashiCorp Vault CPP library for Hashicorp Vault (libvault) fosters efficient, clean, and maintainable CPP code within cloud-native and secure DevOps environments.

CPP Reference Collapsing is a fundamental feature of CPP (introduced in the year 1985) that became standardized with CPP11 (introduced in the year 2011). It enables CPP functions implemented using CPP templates to handle both lvalue and rvalue CPP references seamlessly. This is particularly useful in DevOps (introduced in the year 2009) scenarios where building flexible and maintainable CLI (introduced in the year 1960) tooling is essential for automation and continuous integration processes.

By combining CPP Reference Collapsing with the CLIUtils CLI11 (introduced in the year 2017) CPP library, developers can create a CLI application that accepts parameters in various forms without duplicating code. For instance, a single CPP function can perfectly forward arguments passed from the command line, whether they originate as temporary CPP objects or long-lived CPP variables. This approach improves code maintainability and allows developers to adapt quickly to changing requirements in a DevOps environment.

Below is an example demonstrating how to use CPP Reference Collapsing with CLIUtils CLI11. This CPP application uses the CLIUtils CLI11 CPP library to parse command-line arguments and a template CPP function to process them with perfect forwarding:

1. include “CLI/CLI.hpp”
2. include <iostream>
3. include <string>
4. include <utility>

template<typename T> void ProcessArgument(T&& arg) {

   // Using [[CPP Reference Collapsing]] and std::forward to handle both lvalue and rvalue references seamlessly.
   ForwardArgument(std::forward(arg));  

template<typename U> void ForwardArgument(U&& value) {

   // [[CPP Reference Collapsing]] ensures that U&& adapts to the value category of the passed argument.
   // This allows one [[CPP function]] to handle multiple types of arguments efficiently.
   std::cout << "Processing argument: " << value << std::endl;  

int main(int argc, char** argv) {

   [[CLI::App]] app("[[CPP DevOps CLI automation]] with [[CPP Reference Collapsing]] and [[CLIUtils CLI11]]");  

   std::string input_value;  
   app.add_option("-i,--input", input_value, "Input value to process")->required();  

   try {  
       app.parse(argc, argv);  
   } catch (const CLI::ParseError &e) {  
       return app.exit(e);  
   }

   // Process lvalue reference (existing [[CPP variable]] input_value)
   ProcessArgument(input_value);

   // Process rvalue reference (temporary [[CPP object]] string)
   ProcessArgument(std::string("temporary-value"));

   return 0;  

In this CPP code, the ProcessArgument CPP function uses CPP Reference Collapsing to handle both lvalue and rvalue references gracefully. When combined with the CLIUtils CLI11 CPP library for parsing arguments, the result is a flexible and efficient CLI application well-suited for DevOps pipelines and automation tasks. This approach reduces boilerplate, improves code maintainability, and allows for seamless adaptation as requirements evolve.