Struct ValidationBuilder 

pub struct ValidationBuilder<State = Initial> { /* private fields */ }

Compile-time validation context for DI registrations.

This struct tracks service registrations during the build process and performs validation to catch common configuration errors at compile time.

Validation Rules

• Singleton → Scoped: Error - Singleton services cannot depend on scoped services
• Singleton → Transient: Warning - Singleton will hold the same transient instance forever
• Scoped → Transient: OK - Scoped service gets new transient on each scope resolution
• Missing Dependencies: Error - Required services not registered
• Circular Dependencies: Error - Services that depend on each other in a cycle
• Trait Mismatches: Error - Trait registrations without matching implementations

Examples

use ferrous_di::{ServiceCollection, ValidationBuilder, Lifetime};

struct DatabaseConnection;
struct UserService;  
struct RequestContext;

// This will catch the error at compile time
let validation = ValidationBuilder::new()
    .register::<DatabaseConnection>(Lifetime::Singleton)
    .register::<UserService>(Lifetime::Singleton)
    .depends_on::<UserService, RequestContext>() // RequestContext is scoped!
    .register::<RequestContext>(Lifetime::Scoped)
    .validate();

// Compilation error: Singleton UserService cannot depend on Scoped RequestContext

Implementations

impl ValidationBuilder<Initial>

pub fn new() -> Self

Creates a new validation builder.

pub fn register<T: 'static>(self, lifetime: Lifetime) -> Self

Registers a service with the specified lifetime.

pub fn register_factory<T: 'static, F>(self, lifetime: Lifetime) -> Self

where F: Fn(&ResolverContext<'_>) -> T,

Registers a service factory with the specified lifetime.

pub fn register_trait<T: ?Sized + 'static, I: 'static>( self, lifetime: Lifetime, ) -> Self

Registers a trait implementation.

pub fn depends_on<T: 'static, D: 'static>(self) -> Self

Declares that service T depends on service D.

pub fn validate(self) -> ValidationBuilder<Validated>

Performs validation and transitions to validated state.

pub fn validate_runtime(self) -> ValidationResult

Performs runtime validation (for development/debugging).

impl ValidationBuilder<Validated>

pub fn build(self) -> ServiceCollection

Builds the ServiceCollection with validated configuration.

pub fn get_result(&self) -> ValidationResult

Gets the validation results.

Trait Implementations

impl Default for ValidationBuilder<Initial>

fn default() -> Self

Returns the “default value” for a type.