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## How to use reflection to explore an assembly?
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or
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## How to use reflection to dynamically add a plugin to an application?
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This sample is made of three projects. Be careful with the role and moreover, the links between each other.
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#### 1) ex_036_001_Mammifère.csproj
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This assembly contains a **_Mammifère_** class with a simple **_Name_** property and compiles to a dll in the **_ex_036_001_Reflection\bin_** directory.
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#### 2) ex_036_001_ChatChienOiseau.csproj
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This assembly contains three classes:
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- 2 of them are inheriting from **_Mammifère_** (**_Chat_** and **_Chien_**),
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- the other one is not inheriting from **_Mammifère_** (**_Oiseau_**).
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Important: this assembly references the first one, and compiles to a dll into the **_ex_036_001_Reflection\plugin_** directory.
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#### 3) Applications\ex_036_001_Reflection.csproj
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This assembly compiles to an exe in the **_ex_036_001_Reflection\bin_** directory. It references the first assembly, but **_does not reference_** the second assembly.
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- First, it parses the plugin folder and gets all files :
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```` C#
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DirectoryInfo folder = new DirectoryInfo(Directory.GetCurrentDirectory().ToString()+"..\\..\\..\\plugin\\");F
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ileInfo[] files = folder.GetFiles();
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````
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- Next, it filters these files and launches an assembly analysis on .dll files only
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```` C#
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foreach (FileInfo file in files.Where(f => f.Extension.Equals(".dll")))
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{
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AnalyseDLL(file.FullName);
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}
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````
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- In this **_AnalyseDLL(string filePath)_** method, first, it loads the assembly:
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```` C#
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Assembly a = Assembly.LoadFile(filePath);
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````
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- then, it gets all the exported types of this assembly (all public types):
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```` C#
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Type[] types = a.GetExportedTypes();
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````
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- for each type **_t_** in **_types_**, it then writes its name in the Console, and tests if it's a subclass of **_Animal.Mammifère_**
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```` C#
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Write(t.Name);
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if(t.GetTypeInfo().IsSubclassOf(typeof(Animal.Mammifère)))
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{
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//
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}
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````
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Remember that this Console App does not reference the assembly where the classes **_Chat_**, **_Chien_** and **_Oiseau_** are defined.
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It only references the first assembly with the **_Animal.Mammifère_** class, so
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this is the only class it knows at compile-time. It _discovers_ the others by reflection.
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Now you can explore the types (if they are primitive, interfaces, abstract, delegate, generics ...) and their members (methods, properties...).
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Have fun!
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_Marc Chevaldonné, 27th of may 2019_
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