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I am trying to understand MEF and I am seeing references to MEF and MEF 2.

This site lists MEF2 as being much faster than MEF (4.0).

I need to understand what I am talking about when most people say MEF.

So which is in the .NET Framework 4.5? MEF or MEF2?

Vaccano
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1 Answers1

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Well to make it even more confusing Microsoft released three versions of MEF using two only unique names: MEF and MEF2

  • System.ComponentModel.Composition.* MEF in .NET 4 (typically called just MEF), no support for CompositionScopes, ExportFactories, etc
  • System.ComponentModel.Composition.* MEF2 in .NET 4.5 (sometimes called MEF2 or MEF), support for composition scopes, ExportFactories
  • System.Compostion.* from independent package Microsoft.Composition lightweight version of MEF typically called MEF2

The benchmark site refers to lightweight MEF2 System.Compostion.* from Microsoft.Composition package.

Grzegorz Banczak
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    There's also another one (latest as at April 2019) called [VS-Mef](https://github.com/Microsoft/vs-mef). This would probably be the one to use, as its claimed to be the fastest of all the MEF versons, and more widely compatible with the now-many .NET version families. – Jack Apr 22 '19 at 06:32
  • VS Mef shows only better performance at startup: https://github.com/danielpalme/IocPerformance/issues/120 – BalintPogatsa Aug 08 '19 at 14:26