Io.reader and Io.writer in the go language and their implementation

This is a creation in Article, where the information may have evolved or changed.

In the process of using the go language, whether you are implementing a Web application, console input or output, or network operation, you will inevitably encounter IO operations and use it to IO. Reader and Io.writer interface. may also be familiar with these two interfaces and some related interfaces, but it is very difficult in your mind to form an IO interface inheritance relationship throughout the day, because the Godoc default does not show the official library inheritance as Javadoc, which led to our memory of the IO interface inheritance is not deep, In the use of time also often need to go through the document to deepen memory. This article attempts to comb through the inheritance relationship of the Go IO interface, providing a complete picture of the IO interface.

Io Interface Review

First, let's review a few common IO interfaces. The implementation of the standard library is to subdivide functionality, each with a minimum granularity function defined as an interface, and then the interface can be composed into a more versatile interface.

Minimum-granularity interface

123	type Interface { Read (p []byteint, err Error)}

123	type Interface { Write (p []byteint, err Error)}

123	type Interface { Close () Error}

123	type Interface { int64int) (int64, error)}

123	type Interface { Int64, err Error)}

123	type Interface { Int64, err Error)}

123	type Interface { readat (p []byteint64int, err Error)}

123	type Interface { writeat (p []byteint64int, err Error)}

And

123	type Interface { readbyte () (byte, error)}

123	type Interface { byte) error}

Bytescanner a method more than Bytereader UnreadByte .

1234	type Interface { bytereader unreadbyte () Error}

123	type Interface { runeint, err Error)}

1234	type Interface { runereader unreadrune () Error}

Combination interface

The Go standard library also defines a number of interfaces that are composed of interfaces from the single function above.

1234	type Interface { Reader Closer}

1234	type Interface { Reader Seeker}

1234	type Interface { Reader Writer}

12345

type Interface { Reader Writer Closer}

12345

type Interface { Reader Writer Seeker}

1234	type Interface { Writer Closer}

1234	type Interface { Writer Seeker}

As can be seen from their definition, they are a combination of the smallest granularity.

Extension of the minimum interface

Some struct structs implement and extend the interfaces, which are.

1234	type struct { //Underlying reader Int64 //Max bytes remaining}

123	type struct { //contains filtered or unexportedfields}

123	type struct { //contains filtered or unexportedfields}

123	type struct { //contains filtered or unexportedfields}

Below I will draw their inheritance relationship.

Some auxiliary methods

Some helper methods can generate special types of reader or writer:

12345

func Int64) Readerfunc multireader (Readers ... Reader) Reader func teereader (R Reader, W Writer) readerfunc multiwriter (writers ... Writer) writer

Inheritance relationship

Of course, the go language does not have the same inheritance as in Java, but is implemented based on the duck type, and I try to demonstrate the inheritance of the Go IO interface.

Where yellow is the bufio type under the package,
Green is the archive.tar type under the package,
Blue is the bytes type under the bag,
Pink is the strings type under the bag,
Purple is the crypto.tls type under the bag.

RandIs the math.rand type under the package.
Fileis the os content under the package.
The one on the left of ' Rand ' Reader is the image.jpeg content below.

Our most commonly used is the package io , bytes and bufio under the type, so the types of these packages to remember, in the third library often appear in their shadow.

It is not put mime/multipart.File and net/http.File listed, mainly the diagram is too complex, they implement the interface and os.File similar.

Of course you may ask, how do you organize their inheritance relationships? In fact, you can godoc -analysis=type -http=:6060 create a go doc with an inheritance relationship, and it can also show the inheritance relationships in the libraries you download locally.

Reference documents

1. https://golang.org/pkg/io/
2. https://golang.org/pkg/bufio/
3. https://golang.org/pkg/bytes/
4. https://medium.com/@benbjohnson/go-walkthrough-io-package-8ac5e95a9fbd#.er7vmwvb3
5. https:// medium.com/@blumenmann/a-simple-beginners-tutorial-to-io-writer-in-golang-2a13bfefea02#.sm0gq7rn0
6. https://www.reddit.com/r/golang/comments/4z2eo2/noob_question_how_to_discover_interface/