![]() Let’s assume that you are implementing a custom command engine for a shell program, and you need to run Go functions based on user-entered commands. Inspecting methods and calling them by their string names The above code is indeed dynamic, meaning that it will work even if you add a new field for the Book struct. The for loop assembles all things together and shows a summary of the Book struct. The Field function returns a StructField instance that holds struct field details based on the provided index.Īlso, the Interface function returns the stored value of the selected struct field. The NumField function returns the number of fields of the given struct instance. Look at the following code that prints the types of several variables. Inspecting the types of variablesįirst, we can inspect the variable types to get started with the reflect package. Since Go is a statically-typed compiled language, its reflection API is created based on two key components: reflection Type and Value. The Go reflection package offers us runtime reflection, so these examples inspect or manipulate the program structure during the execution time. Now that we’ve covered the the theoretical concept behind the reflection, let’s get started with practical examples. Also, I’ll show you how to build a simple shell program with reflection API. The following tutorial section will cover all of the fundamentals you need to implement the above use cases. e.g., you can find existing methods of a struct and call them by name.We can dynamically execute code with the help of the reflection API.Since reflection offers a way to examine the program structure, it is possible to build static code analyzers by using it.e.g., if you are using a struct instance to build a SQL query, you can use reflection to extract struct fields without hardcoding every struct field name.Programmers can use reflection to solve programming problems with less code.You may be thinking, you already know about your program’s source code, so why do you even need to inspect the code you wrote via reflection? But reflection has many helpful use cases, as shown below: The reflection concept typically exposes a native API to inspect or modify the current program. Let’s take a closer look at how this works specifically in the Go programming language. Check an atomic type of an unknown variable with reflection APIs.Check whether a function exists in a struct instance.These APIs are known as reflection APIs, and they serve as a particular programming language’s ability to inspect, manipulate, and execute the structure of the code. Almost all popular languages expose internal APIs to handle metaprogramming for the particular programming language itself. Reflection is a sub-topic of the metaprogramming paradigm. The metaprogramming techniques can inspect and process other programs, or the program itself, even during its execution. Metaprogramming refers to a programming technique that treats the program as data. For example, you can list all the properties of a struct without knowing all of its properties. On the other hand, if we think of source code as data, we can inspect and update it like we do for normal program process data. If we treat the source code as code, it is possible to execute the source code on a CPU like we always do. We can treat our source codes in two ways: as code, and as data. What are metaprogramming and reflection?īefore diving into the tutorial, we need to understand metaprogramming and reflection. ![]() We’ll also walk through metaprogramming and cover some example use cases that you may encounter. In this tutorial, we are going to learn about Go’s reflection API. It also offers a package to work with reflection, which is a concept that comes from the metaprogramming paradigm. Therefore, Go’s standard library has almost all of the features we need for a modern programming language. Rather, the Go language’s development team extends Go’s standard library instead. Go follows a unique design pattern that other modern programming languages typically don’t: it doesn’t modify the language’s grammar. It is gaining more popularity every day in modern developer communities because of features such as memory safety, garbage collection, concurrency, performance, and a developer-friendly minimal syntax. ![]() ![]() The Go programming language is a popular statically-typed, compiled programming language that has a C-like syntax. Shalitha Suranga Follow Programmer | Author of Neutralino.js | Technical Writer Reflection in Go: Use cases and tutorial ![]()
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