---
source_files:
  - Common/DTS.Common/ModuleCatalog/AggregateModuleCatalog.cs
generated_at: "2026-04-17T16:39:46.691018+00:00"
model: "zai-org/GLM-5-FP8"
schema_version: 1
sha256: "9c34696a3d6323c2"
---

# AggregateModuleCatalog Documentation

## 1. Purpose

`AggregateModuleCatalog` is an implementation of `IModuleCatalog` that aggregates multiple module catalogs into a single unified interface. It enables composition of module catalogs from different sources (e.g., configuration files, dynamic discovery, explicit registration) while presenting them as a single catalog to the Prism modularity system. This class delegates operations to the underlying catalogs while coordinating results across all of them.

## 2. Public Interface

### Constructor

```csharp
public AggregateModuleCatalog()
```
Initializes a new instance with a default `ModuleCatalog` as the first catalog in the aggregate collection.

---

### AddCatalog

```csharp
public void AddCatalog(IModuleCatalog catalog)
```
Adds a module catalog to the aggregate collection. Throws `ArgumentNullException` if `catalog` is null.

---

### Modules

```csharp
public IEnumerable<ModuleInfo> Modules { get; }
```
Returns all `ModuleInfo` instances across all aggregated catalogs by projecting and flattening each catalog's `Modules` property.

---

### GetDependentModules

```csharp
public IEnumerable<ModuleInfo> GetDependentModules(ModuleInfo moduleInfo)
```
Locates the catalog containing `moduleInfo` and returns its dependencies. Uses `Single()` to find the owning catalog, meaning the module must exist in exactly one catalog or an exception will be thrown.

---

### CompleteListWithDependencies

```csharp
public IEnumerable<ModuleInfo> CompleteListWithDependencies(IEnumerable<ModuleInfo> modules)
```
Returns the complete list of modules including all transitive dependencies. Groups modules by their owning catalog and delegates to each catalog's `CompleteListWithDependencies` method.

---

### Initialize

```csharp
public void Initialize()
```
Iterates through all catalogs and calls `Initialize()` on each one.

---

### AddModule

```csharp
public void AddModule(ModuleInfo moduleInfo)
```
Adds a `ModuleInfo` to the first catalog in the collection (the default `ModuleCatalog` created in the constructor).

## 3. Invariants

- **Non-empty catalog collection**: The `_catalogs` list always contains at least one catalog after construction (the default `ModuleCatalog` at index 0).
- **Module uniqueness assumption**: `GetDependentModules` and `CompleteListWithDependencies` assume each `ModuleInfo` exists in exactly one catalog. The use of `Single()` enforces this—if a module is not found or found in multiple catalogs, an exception will be thrown.
- **Null rejection**: `AddCatalog` will not accept null catalogs and throws `ArgumentNullException`.

## 4. Dependencies

### This module depends on:
- `Microsoft.Practices.Prism.Modularity` — Provides `IModuleCatalog`, `ModuleInfo`, and `ModuleCatalog` types from the Prism library.
- `System`, `System.Collections.Generic`, `System.Linq` — Standard .NET framework types.

### What depends on this module:
- **Unc