Generate config pattern.
Given
package example
// ...
run goconfig -field "Size int|ErrorHandling flag.ErrorHandling" -option
then generate
package example
import "flag"
type ConfigItem[T any] struct {
modified bool
value T
defaultValue T
}
func (s *ConfigItem[T]) Set(value T) {
s.modified = true
s.value = value
}
func (s *ConfigItem[T]) Get() T {
if s.modified {
return s.value
}
return s.defaultValue
}
func (s *ConfigItem[T]) Default() T {
return s.defaultValue
}
func (s *ConfigItem[T]) IsModified() bool {
return s.modified
}
func NewConfigItem[T any](defaultValue T) *ConfigItem[T] {
return &ConfigItem[T]{
defaultValue: defaultValue,
}
}
type Config struct {
Size *ConfigItem[int]
ErrorHandling *ConfigItem[flag.ErrorHandling]
}
type ConfigBuilder struct {
size int
errorHandling flag.ErrorHandling
}
func (s *ConfigBuilder) Size(v int) *ConfigBuilder {
s.size = v
return s
}
func (s *ConfigBuilder) ErrorHandling(v flag.ErrorHandling) *ConfigBuilder {
s.errorHandling = v
return s
}
func (s *ConfigBuilder) Build() *Config {
return &Config{
Size: NewConfigItem(s.size),
ErrorHandling: NewConfigItem(s.errorHandling),
}
}
func NewConfigBuilder() *ConfigBuilder { return &ConfigBuilder{} }
func (s *Config) Apply(opt ...ConfigOption) {
for _, x := range opt {
x(s)
}
}
type ConfigOption func(*Config)
func WithSize(v int) ConfigOption {
return func(c *Config) {
c.Size.Set(v)
}
}
func WithErrorHandling(v flag.ErrorHandling) ConfigOption {
return func(c *Config) {
c.ErrorHandling.Set(v)
}
}
in config.go in the same directory.