Naming convention

 

Interface names

By convention, one-method interfaces are named by the method name plus an -er suffix or similar modification to construct an agent noun: Reader, Writer, Formatter, CloseNotifier etc.

MixedCaps

Finally, the convention in Go is to use MixedCaps or mixedCaps rather than underscores to write multiword names.

Getters

It's neither idiomatic nor necessary to put Get into the getter's name. If you have a field called owner (lower case, unexported), the getter method should be called Owner (upper case, exported), not GetOwner. The use of upper-case names for export provides the hook to discriminate the field from the method. A setter function, if needed, will likely be called SetOwner. Both names read well in practice:

owner := obj.Owner()

if owner != user {

    obj.SetOwner(user)

}

They even have semantic effect: the visibility of a name outside a package is determined by whether its first character is upper case.

Package names ¶

When a package is imported, the package name becomes an accessor for the contents. After

import "bytes"

the importing package can talk about bytes.Buffer. It's helpful if everyone using the package can use the same name to refer to its contents, which implies that the package name should be good: short, concise, evocative. By convention, packages are given lower case, single-word names; there should be no need for underscores or mixedCaps. Another convention is that the package name is the base name of its source directory; the package in src/encoding/base64 is imported as "encoding/base64" but has name base64, not encoding_base64 and not encodingBase64. 

The importer of a package will use the name to refer to its contents,  For instance, the buffered reader type in the bufio package is called Reader, not BufReader, because users see it as bufio.Reader, which is a clear, concise name. Moreover, because imported entities are always addressed with their package name, bufio.Reader does not conflict with io.Reader. Similarly, the function to make new instances of ring.Ring—which is the definition of a constructor in Go—would normally be called NewRing, but since Ring is the only type exported by the package, and since the package is called ring, it's called just New, which clients of the package see as ring.New. Use the package structure to help you choose good names.

Another short example is once.Do; once.Do(setup) reads well and would not be improved by writing once.DoOrWaitUntilDone(setup).

 The gofmt program (also available as go fmt, which operates at the package level rather than source file level) reads a Go program and emits the source in a standard style of indentation and vertical alignment, retaining and if necessary reformatting comments. If you want to know how to handle some new layout situation, run gofmt; if the answer doesn't seem right, rearrange your program (or file a bug about gofmt), don't work around it.

As an example, there's no need to spend time lining up the comments on the fields of a structure. Gofmt will do that for you. Given the declaration

type T struct {
    name string // name of the object
    value int // its value
}

gofmt will line up the columns:

type T struct {
    name    string // name of the object
    value   int    // its value
}

All Go code in the standard packages has been formatted with gofmt.

Some formatting details remain. Very briefly:

Indentation

We use tabs for indentation and gofmt emits them by default. Use spaces only if you must.

Line length

Go has no line length limit. Don't worry about overflowing a punched card. If a line feels too long, wrap it and indent with an extra tab.

Parentheses

Go needs fewer parentheses than C and Java: control structures (if, for, switch) do not have parentheses in their syntax. Also, the operator precedence hierarchy is shorter and clearer, so

x<<8 + y<<16

means what the spacing implies, unlike in the other languages.

When a package is imported, the package name becomes an accessor for the contents. After

import "bytes"

the importing package can talk about bytes.Buffer. It's helpful if everyone using the package can use the same name to refer to its contents, which implies that the package name should be good: short, concise, evocative. By convention, packages are given lower case, single-word names; there should be no need for underscores or mixedCaps.

Another convention is that the package name is the base name of its source directory; the package in src/encoding/base64 is imported as "encoding/base64" but has name base64, not encoding_base64 and not encodingBase64.

The importer of a package will use the name to refer to its contents,  For instance, the buffered reader type in the bufio package is called Reader, not BufReader, because users see it as bufio.Reader, which is a clear, concise name. Moreover, because imported entities are always addressed with their package name, bufio.Reader does not conflict with io.Reader. Similarly, the function to make new instances of ring.Ring—which is the definition of a constructor in Go—would normally be called NewRing, but since Ring is the only type exported by the package, and since the package is called ring, it's called just New, which clients of the package see as ring.New. Use the package structure to help you choose good names.

Another short example is once.Do; once.Do(setup) reads well and would not be improved by writing once.DoOrWaitUntilDone(setup). Long names don't automatically make things more readable.

Go's declaration syntax allows grouping of declarations. A single doc comment can introduce a group of related constants or variables. // Error codes returned by failures to parse an expression.

var (
    ErrInternal      = errors.New("regexp: internal error")
    ErrUnmatchedLpar = errors.New("regexp: unmatched '('")
    ErrUnmatchedRpar = errors.New("regexp: unmatched ')'")
    ...
)

Grouping can also indicate relationships between items, such as the fact that a set of variables is protected by a mutex.

var (
    countLock   sync.Mutex
    inputCount  uint32
    outputCount uint32
    errorCount  uint32
)