Add context

[ynishi]

• user can set some options.
• like debug log level list for is_debug.
• create EnvTypeContext and provide default and global.

[ynishi]

• Enum with Option
• create new builder, input: config and some From, output EnvType
• new 2 param From

enum EnvType {
  Dev(Option)
}

struct Option {
  is_debug: bool
}

struct Config{
  debugs: Vec<EnvType>
}

trait FromWithContext<V, C> {
  from_with_context(value: V, context: C) -> Self
}

impl FromWithContext<T, Config> for EnvType {
  from_with_context(value: V, context: C) -> Self
    where V: From<V>::EnvType {
      ...
  }
}

[ynishi]

Extensible Environment Type System Design

Core Components

1. Environment Type System

The environment type system consists of several key layers that enable extensibility and type safety.

// Base environment traits and types
pub trait Environment: Send + Sync + 'static {
    fn name(&self) -> &str;
    fn env_type(&self) -> &EnvType;
    fn is_debug(&self) -> bool;
    fn features(&self) -> &FeatureSet;
    fn resource_limits(&self) -> &ResourceLimits;
    fn config<T: Config>(&self) -> Option<&T>;
}

2. Configuration Management

Configuration handling is implemented through traits and type-safe interfaces.

pub trait Config: Send + Sync + 'static {
    fn validate(&self) -> Result<(), ConfigError>;
    fn merge(&self, other: &Self) -> Result<Self, ConfigError> where Self: Sized;
}

pub trait ConfigProvider: Send + Sync {
    type Config: Config;
    type Error: std::error::Error;

    async fn load(&self) -> Result<Self::Config, Self::Error>;
    async fn save(&self, config: &Self::Config) -> Result<(), Self::Error>;
}

3. Environment Behavior

Environment-specific behaviors are defined through extensible traits.

#[async_trait]
pub trait EnvironmentBehavior: Send + Sync {
    type Config: Config;
    type Error: std::error::Error;

    async fn initialize(&self, config: &Self::Config) -> Result<(), Self::Error>;
    async fn cleanup(&self) -> Result<(), Self::Error>;

    fn get_features(&self) -> &FeatureSet;
    fn get_resource_limits(&self) -> &ResourceLimits;
}

Extension Points

1. Custom Environments

// Custom environment implementation
pub struct CustomEnvironment<T: Config> {
    name: String,
    env_type: EnvType,
    config: T,
    features: FeatureSet,
    resource_limits: ResourceLimits,
}

impl<T: Config> Environment for CustomEnvironment<T> {
    // Implementation details
}

2. Behavior Extensions

pub trait BehaviorExtension {
    fn extend(&mut self, behavior: Box<dyn EnvironmentBehavior>);
    fn modify_features(&mut self, modifier: Box<dyn Fn(&mut FeatureSet)>);
}

3. Configuration Extensions

pub trait ConfigExtension {
    fn with_override<T: Config>(&self, override_config: T) -> Result<Self, ConfigError> 
    where Self: Sized;

    fn merge_from<T: Config>(&mut self, other: &T) -> Result<(), ConfigError>;
}

Type Safety and Validation

1. Type-Safe Configuration

pub trait TypedConfig<E: Environment> {
    type Output;

    fn get_typed_config(&self) -> Result<Self::Output, ConfigError>;
}

2. Environment Constraints

pub trait EnvironmentConstraint {
    fn validate_constraints(&self) -> Result<(), ConstraintError>;
    fn check_compatibility<T: Environment>(&self) -> bool;
}

Management and Monitoring

1. Environment Manager

pub struct EnvironmentManager {
    environments: HashMap<TypeId, Box<dyn Environment>>,
    behaviors: HashMap<TypeId, Box<dyn EnvironmentBehavior>>,
    config_providers: HashMap<TypeId, Box<dyn ConfigProvider>>,
}

2. Monitoring System

pub trait EnvironmentMonitor {
    fn on_config_change(&self, old_config: &dyn Config, new_config: &dyn Config);
    fn on_feature_change(&self, feature: &str, enabled: bool);
    fn on_resource_limit_change(&self, resource: &str, limit: &ResourceLimit);
}

Implementation Patterns

1. Builder Pattern

pub struct EnvironmentBuilder<E: Environment> {
    env_type: EnvType,
    config: Option<Box<dyn Config>>,
    behavior: Option<Box<dyn EnvironmentBehavior>>,
    features: FeatureSet,
    resource_limits: ResourceLimits,
}

2. Factory Pattern

pub trait EnvironmentFactory {
    type Environment: Environment;
    type Config: Config;
    type Error: std::error::Error;

    fn create(
        &self,
        config: Self::Config,
        behavior: Box<dyn EnvironmentBehavior>,
    ) -> Result<Self::Environment, Self::Error>;
}

Usage Examples

1. Basic Usage

// Create a new environment
let env_builder = EnvironmentBuilder::new(EnvType::Development)
    .with_config(DevConfig::default())
    .with_behavior(DevBehavior::new())
    .enable_feature("debug_logging");

let env = env_builder.build()?;

2. Custom Environment

let custom_env = CustomEnvironment::new(
    "staging-east",
    CustomConfig {
        resource_limits: ResourceLimits::new()
            .with_memory_limit(1024)
            .with_connection_limit(100),
        features: FeatureSet::new()
            .enable("beta_features")
            .enable("monitoring"),
    }
);

3. Configuration Management

// Load and merge configurations
let base_config = config_provider.load_base_config()?;
let env_config = config_provider.load_env_specific_config()?;
let final_config = base_config.merge(&env_config)?;

// Apply configuration
env.apply_config(final_config)?;

Best Practices

1. Type Safety

   • Use strong typing for configurations
   • Implement proper trait bounds
   • Validate at compile time when possible

2. Extension Points

   • Design for extensibility
   • Use trait objects for behavior extensions
   • Implement proper lifecycle management

3. Error Handling

   • Use specific error types
   • Implement proper error propagation
   • Provide meaningful error messages

4. Resource Management

   • Implement proper cleanup
   • Use RAII principles
   • Monitor resource usage

Considerations

1. Performance

   • Minimize runtime overhead
   • Use static dispatch where possible
   • Implement efficient resource management

2. Safety

   • Ensure thread safety
   • Implement proper validation
   • Handle edge cases

3. Maintainability

   • Follow SOLID principles
   • Document extension points
   • Provide clear examples

This design provides a flexible and type-safe foundation for building extensible environment-specific configurations and behaviors in Rust applications.