run-time reflection means in go

In Go, runtime reflection refers to the ability of a program to examine its own structure and behavior at runtime. This allows the program to inspect and manipulate its own objects, types, and functions dynamically.

The reflect package

The reflect package in Go provides a set of functions and types that enable runtime reflection. It allows you to examine the structure and properties of objects, and perform operations such as creating new objects, calling methods dynamically, and accessing and modifying fields.

The reflect.Value type

The reflect package introduces the reflect.Value type, which represents a value of any type. This type allows you to inspect and manipulate the underlying value, regardless of its original type. You can obtain a reflect.Value object using the reflect.ValueOf() function.

Inspecting the type of a value

You can use the Type() method of a reflect.Value object to obtain the type information of the underlying value. This allows you to determine the kind of the value, such as whether it is an integer, string, struct, or function.

Accessing and modifying fields

If the underlying value is a struct, you can use the Field() method of a reflect.Value object to access and modify its fields dynamically. The Field() method takes an index representing the field position and returns a new reflect.Value object representing the field.

Invoking methods dynamically

If the underlying value is a struct or a pointer to a struct, you can use the MethodByName() method of a reflect.Value object to invoke methods dynamically. The MethodByName() method takes the name of the method as a string and returns a new reflect.Value object representing the method. You can then call the method using the Call() method of the reflect.Value object.

Creating new objects

The reflect package also provides functions such as New() and NewAt() that allow you to create new objects of a specific type dynamically. These functions return a reflect.Value object representing the newly created object.

Performance considerations

It's important to note that runtime reflection in Go can have performance implications. Reflection operations are generally slower than their statically typed counterparts, as they involve dynamic type checks and additional indirection. Therefore, it's recommended to use reflection sparingly and only when necessary.

Conclusion

In summary, runtime reflection in Go allows a program to examine and manipulate its own structure and behavior dynamically. The reflect package provides functions and types for performing reflection operations, such as inspecting types, accessing and modifying fields, invoking methods, and creating new objects. However, it's important to consider the performance implications of using reflection and use it judiciously.