Why is `*http.Request` a Pointer but `http.ResponseWriter` is Not in Go HTTP Handlers?

Pointers in HTTP Handlers

In Go, the signature of an HTTP handler function typically resembles this:

func handle(w http.ResponseWriter, r *http.Request) {}

This signature raises a question for newcomers to pointers: why is the Request object a pointer, while the ResponseWriter is not?

To understand this, it's crucial to delve into the specifics of both types.

The ResponseWriter represents the HTTP response object. However, beneath the surface, it's actually a pointer to an unexported type called http.response, which encapsulates the internals of HTTP response handling. Since ResponseWriter is an interface, this underlying implementation is not exposed.

In contrast, the Request object is a pointer to a concrete structure (Request), which contains fields representing various aspects of the HTTP request, such as headers, body, and URL information. Unlike the ResponseWriter, which manages the server's response, the Request object is primarily used to access the client's request data. Passing it as a pointer allows the handler to modify request parameters directly, if necessary.

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