Created
March 23, 2023 20:21
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Variadic Example
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package main | |
import ( | |
"context" | |
"errors" | |
"fmt" | |
) | |
type ( | |
Service struct { | |
logger interface{} | |
db interface{} | |
} | |
ServiceOption func(*Service) error | |
) | |
func WithLogger(logger interface{}) ServiceOption { | |
return func(s *Service) error { | |
if logger == nil { | |
return errors.New("invalid logger") | |
} | |
s.logger = logger | |
} | |
} | |
func NewService(options ...ServiceOption) (*Service, error) { | |
s := &Service{ | |
db: nil, | |
logger: nil, | |
} | |
for _, opt := range options { | |
if err := opt(s); err != nil { | |
return nil, err | |
} | |
} | |
return s, nil | |
} | |
type writeArgs struct { | |
file io.File | |
logger interface{} | |
db interface{} | |
} | |
type Option func(args *writeArgs) error | |
func WithLogger(logger interface{}) Option { | |
return func(args *writeArgs) error { | |
if logger == nil { | |
return errors.New("invalid logger") | |
} | |
args.logger = logger | |
} | |
} | |
func (s *Service) Write(ctx context.Context, file io.File, options ...Option) error { | |
args := &writeArgs{ | |
logger: s.logger, | |
db: s.db, | |
file: file, | |
} | |
for _, option := range options { | |
if err := option(args); err != nil { | |
return fmt.Errorf("failed to overwrite write arguments: %w", err) | |
} | |
} | |
// do things with args | |
return nil | |
} |
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