MEF and DirectoryCatalog

Question

是否有一种方法可以安全地使用DirectoryCatalog来处理目录不存在的情况?

下面是我的容器如何设置的代码示例:

    //Create an assembly catalog of the assemblies with exports
    var catalog = new AggregateCatalog(
        new AssemblyCatalog(Assembly.GetExecutingAssembly()),
        new AssemblyCatalog(Assembly.Load("My.Second.Assembly")),
        new DirectoryCatalog("Plugins", "*.dll"));
    //Create a composition container
    var container = new CompositionContainer(catalog);

但是如果目录不存在会抛出异常，我想忽略这个错误。

Answer 1

如果抛出异常显然不会。只要在运行MEF容器安装程序之前创建目录，就不会抛出错误。

根据文档:

路径必须为AppDomain.BaseDirectory的绝对路径或相对路径。

PsuedoCode执行目录检查:

    string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Plugins");
    //Check the directory exists
    if (!Directory.Exists(path))
    {
        Directory.CreateDirectory(path);
    }
    //Create an assembly catalog of the assemblies with exports
    var catalog = new AggregateCatalog(
        new AssemblyCatalog(Assembly.GetExecutingAssembly()),
        new AssemblyCatalog(Assembly.Load("My.Other.Assembly")),
        new DirectoryCatalog(path, "*.dll"));
    //Create a composition container
    _container = new CompositionContainer(catalog);