Modular Architecture

Nidus structures applications as a tree of modules (TModule), each encapsulating a cohesive slice of functionality. This mirrors the NestJS module pattern.

The [Module] attribute

Decorate every module class with [Module] so that Nidus can inspect the type via RTTI at startup:

type
  [Module]
  TUserModule = class(TModule)
  public
    procedure Configure(const ABuilder: IModuleBuilder); override;
  end;

Declaring providers

Inside Configure, use IModuleBuilder to register providers and exports:

procedure TUserModule.Configure(const ABuilder: IModuleBuilder);
begin
  ABuilder
    .AddProvider(TBind<TUserService>.Singleton)
    .AddProvider(TBind<TUserRepository>.Factory)
    .Export(TUserService);   // expose TUserService to importing modules
end;

Bind strategies

Method	Lifecycle	Description
TBind<T>.Singleton	One instance per app	Created once, reused forever
TBind<T>.SingletonLazy	Lazy singleton	Created on first Get<T> call
TBind<T>.Factory	Per-resolution	New instance on every Get<T>
TBind<T>.SingletonInterface<I>	Singleton via interface	Registered under interface I
TBind<T>.AddInstance	Manual	Registers a pre-built instance

Source: Nidus.Bind (TBind<T>, TSingletonBind<T>, TFactoryBind<T>, …)

Importing modules

A module can import another module to consume its exported providers:

type
  [Module]
  TAppModule = class(TModule)
  public
    procedure Configure(const ABuilder: IModuleBuilder); override;
  end;

procedure TAppModule.Configure(const ABuilder: IModuleBuilder);
begin
  ABuilder
    .Import(TUserModule)
    .Import(TOrderModule);
end;

Resolving services

After TNidus.Start, resolve any exported service by type:

var LSvc := GetNidus.Get<TUserService>;

Or by interface:

var IRepo := GetNidus.GetInterface<IUserRepository>;

Route modules (lazy loading)

Modules can be loaded and disposed per HTTP request via the route mechanism:

// inside a Horse middleware or route handler:
GetNidus.LoadRouteModule('/users/create', LRequest);

// after the request, dispose the module tree for that path:
GetNidus.DisposeRouteModule('/users/create');

TModuleProvider.DisposeModule walks the path segments and frees each module instance, unless the module is pinned by the cache policy.