pragma

Documentation

Overview

Package pragma provides types that can be embedded into a struct to statically enforce or prevent certain language properties. The key observation and some code (shr) is borrowed from https://github.com/protocolbuffers/protobuf-go/blob/v1.25.0/internal/pragma/pragma.go

Index

• type CopyChecker
  • func (c *CopyChecker) Check()
  • func (c *CopyChecker) Copied() bool
• type DoNotCompare
• type DoNotCopy
• type DoNotImplement
• type NoUnkeyedLiterals

Examples

• CopyChecker
• DoNotCompare
• DoNotCopy
• DoNotImplement
• NoUnkeyedLiterals

Types

type CopyChecker

type CopyChecker uintptr

CopyChecker holds back pointer to itself to detect object copying. Deprecated. use DoNotCopy instead, check by go vet. methods Copied or Check return not copied if none of methods Copied or Check have bee called before

Example

Output:

a copied : false
a copied : false
a copied : false
b copied : true

func (*CopyChecker) Check

func (c *CopyChecker) Check()

Check panic is c is copied

func (*CopyChecker) Copied

func (c *CopyChecker) Copied() bool

Copied returns true if this object is copied

type DoNotCompare

type DoNotCompare [0]func()

DoNotCompare can be embedded in a struct to prevent comparability.

Example

Output:

Invalid operation: a == b (operator == is not defined on DoNotCompare)

type DoNotCopy

type DoNotCopy [0]sync.Mutex

DoNotCopy can be embedded in a struct to help prevent shallow copies. This does not rely on a Go language feature, but rather a special case within the vet checker.

See https://golang.org/issues/8005.

Example

Output:

Assignment copies lock value to '_': type 'DoNotCopy' contains 'sync.Mutex' which is 'sync.Locker'

type DoNotImplement

type DoNotImplement interface{ ProtoInternal(doNotImplement) }

Example

Output:

cannot use &a (type *DoNotImplementStruct) as type DoNotImplement in assignment:

type NoUnkeyedLiterals

type NoUnkeyedLiterals struct{}

NoUnkeyedLiterals can be embedded in a struct to prevent unkeyed literals.

Example

Output:

cannot convert "Name" (untyped string constant) to pragma.NoUnkeyedLiterals