---

name: patterns description: Project patterns including functional options, must pattern, caching decorator, error handling, configuration, and HTTP clients. Use when implementing common patterns in the codebase. userInvokable: true

Project Patterns

References: Examples

Functional Options

Example

Use With* functions for configurable constructors:

Copyfunc NewClient(baseURL string, options ...ClientOption) *Client {
    opts := defaultOptions()
    for _, option := range options {
        option(opts)
    }
    // create client...
}

client := NewClient(url, WithTimeout(30*time.Second), WithRetryCount(3))

Must Pattern

Example

Allowed only in cmd/, internal/apps/ - to fail fast on misconfiguration.

Copyfunc Must[T any](f func() (T, error)) T {
    v, err := f()
    if err != nil { panic(err) }
    return v
}

Caching Decorator

Example

Wrap clients with cache layer for transparent caching.

Error Handling

Example

Configuration

Example

Rules: No ARNs in app config, no secrets in files, use time.Duration with custom unmarshaler

HTTP Client with Retry

Example

Copyclient := tracing.NewRestyClient(baseURL,
    tracing.WithTimeout(30*time.Second),
    tracing.WithRetryCount(3),
    tracing.WithExponentialBackoff(true),
)

DynamoDB Key Design

Example

Use composite keys (PK + SK), GSIs for query patterns.

Feature Flags

Example

Fallback defaults, check at service layer, log evaluations.

JSON Tags

Example

Use camelCase for JSON tags and query params.

Request Validation

Example

Use ozzo-validation for struct validation.

Libraries