Namespaces¶

A namespace is the unit within which a private declaration may be used. By default each file is its own namespace, named after the file.

File	Namespace
`user_repository.go`	`userRepository`
`user_repository_test.go`	`userRepository`. A test shares the namespace of its subject
`parser_linux.go`	`parser`. A GOOS or GOARCH suffix is a build constraint, not a namespace
`parser_test_linux.go`	`parserTest`. As in go/build, only a name ending in `_test.go` is a test
`parser_linux.pb.go`, `parser.x_linux.go`	`parserPb`, `parserXLinux`. As in go/build, a suffix counts only before the first dot
`user_id.go`, `user_ids.go`, `parse_json.go`	`userID`, `userIDs`, `parseJSON`. An initialism, or its plural, is spelled the way Go spells it
`foo-bar.go`, `Foo.go`	`fooBar`, `foo`. Any separator, and a PascalCase stem, become lowerCamelCase
`HTTPServer.go`, `URLs.go`, `IPv4.go`	`httpServer`, `urls`, `ipv4`. A leading initialism is lowered the way Go lowers one
`2fa_auth.go`, `用户.go`	`2faAuth`, `用户`. Valid namespaces, but never a prefix: the first character must be a letter with a capital form

The namespace comes from the file name and is not equal to it. So you can rename a file without renaming what it declares.

Files join an explicitly named namespace with a directive before the package clause. This is how one unit spans several files. The name must be an unexported identifier.

//declscope:namespace user
package repo

The core namespace¶

One namespace in a package may be its core: the unit the package is named for. Several files may carry //declscope:core, and they share the one core namespace.

// client.go
//declscope:core

package transport

The core has no prefix, so the naming rule asks nothing of its declarations. No prefix still names exactly one unit.

A test file joins the core when it tests a core file, as client_test.go tests client.go. The test file is matched by its whole name, so client_linux_test.go joins a core client_linux.go but not a core client.go. Only a test file joins: a core client_test.go does not take client.go into the core, and a core client_linux.go does not take client.go. A test file that names its own namespace with //declscope:namespace keeps it.

Important

//declscope:core sets the namespace and nothing else. It carries no scope. A core declaration still takes defaults.unexported: by default it is private to the core, and a file outside the core that names it crosses a boundary.

Written on a file	Effect
`//declscope:core`	The file joins the core. What it declares keeps the default scope
`//declscope:core` and `//declscope:shared`	Both apply. The file is core, and what it declares is package-wide
`//declscope:core` and `//declscope:namespace`	Refused. A core file's namespace is the core