golint-sl

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contextfirst

About 245 words

Ensures context.Context is the first parameter in function signatures.

Category

Architecture

What It Checks

This analyzer detects functions where context.Context is not the first parameter. The reported position counts every parameter name, so in func f(a, b int, ctx context.Context) the context is parameter 3.

Only the standard library's context.Context (or an alias of it) counts. Framework types that are also called Context, such as *gin.Context, are not checked.

Why It Matters

Go convention: context is always first. This:

  • Makes code consistent and predictable
  • Allows easy visual scanning for context usage
  • Follows standard library conventions

Examples

Bad

func GetUser(id string, ctx context.Context) (*User, error) {
    // Context buried in parameters
}

func ProcessOrder(order *Order, ctx context.Context, opts ...Option) error {
    // Context in the middle
}

Good

func GetUser(ctx context.Context, id string) (*User, error) {
    // Context is first
}

func ProcessOrder(ctx context.Context, order *Order, opts ...Option) error {
    // Context is first, variadic opts are last
}

Parameter Order Convention

func DoSomething(
    ctx context.Context,     // 1. Context first
    requiredParam Type,      // 2. Required parameters
    optionalParam *Type,     // 3. Optional parameters
    opts ...Option,          // 4. Variadic options last
) error

Configuration

# .golint-sl.yaml
analyzers:
  contextfirst: true  # enabled by default

When to Disable

  • Interface implementations that must match external signatures
  • CGO or interop code
analyzers:
  contextfirst: false

See Also