Question

When I run my script directly from the Powershell console it works. When I run my script in PowerGUI and try instantiate an object, I get an error:

Exception calling “.ctor” with “3” argument(s): “Could not load file or assembly ‘MyLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=77f676cc8f85d94e’ or one of its dependencies. The system cannot find the file specified.”

If I put all of the needed DLLs in $PSHOME, the script will successfully run from the console but not PowerGUI. If I move the DLLs to a local directory and load the DLLs with reflection, the script will not run in PowerGUI nor the powershell console.

[reflection.assembly]::loadfile(‘c:\mylibs\mylib.dll’)

What do I need to do to get the script to run in PowerGUI? Ideally, I’d like the DLLs in a different directory than $PSHOME.

Answer 1

You should be using [Assembly]::LoadFrom as opposed to LoadFile. LoadFile is intended for loading assemblies that cannot be loaded in the normal assembly loading context such as the case where you are trying to load two versions of the same assembly. It does not use the normal probing rules so that is why it doesn’t automatically load dependencies. Here’s an excerpt from the documentation for LoadFile.

Use the LoadFile method to load and
examine assemblies that have the same
identity, but are located in different
paths. LoadFile does not load files
into the LoadFrom context, and does
not resolve dependencies using the
load path, as the LoadFrom method
does. LoadFile is useful in this
limited scenario because LoadFrom
cannot be used to load assemblies that
have the same identities but different
paths; it will load only the first
such assembly.

If you are using PowerShell 2.0 you may wish to use Add-Type instead:

Add-Type -Path c:\mylibs\mylib.dll

And if all else fails, run Fuslogvw.exe to find out why binding fails.