Calling a Python script with Arguments using IronPython - "Need more than x values to unpack"

I'm using the following C# code to call a Python script using IronPython:

ScriptEngine scriptEngine;

var opts = new Dictionary<string, objec开发者_如何学JAVAt>();
opts["Arguments"] = new[] { 
    Server.MapPath(@"~\Processing\input.7z"), // Input
    Server.MapPath(@"~\Processing\key.pem"),  // Key
    Server.MapPath(@"~\Processing\") };       // Output
        scriptEngine = Python.CreateEngine(opts);

var sp = scriptEngine.GetSearchPaths();
sp.Add(Server.MapPath(@"~\python\lib"));
scriptEngine.SetSearchPaths(sp);

var scope = scriptEngine.Runtime.ExecuteFile(Server.MapPath(@"~\python\test.py"));

The script takes the following arguments:

arg0,input,key,output = sys.argv

I'm getting the error "Need more than 3 values to unpack". What am I doing wrong?

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The line

arg0,input,key,output = sys.argv

unpacks the list of arguments in sys.argv into the four variables on the left. Since there are only three arguments in sys.argv, this fails with the error message you posted (apparently you need to manually pass in the script path for it to appear as the first element in sys.argv).

Try a different way of passing in command-line arguments (from this answer):

scriptEngine.Sys.argv = List.Make(new[] { 'input.7z', ... });

Alternatively, if that doesn't work, then either remove the arg0 variable from the assignment in the Python file, or add the script's path explicitly as the first argument in C#.

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Well the literal meaning of that error is that sys.argv contains only 3 values, but you've got 4 variables there. (The error message that you'd get if you were trying to unpack 4 values into 3 variables would be "too many values to unpack".)

Why there's no arg0 in sys.argv, I don't know -- I can only assume that it has something to do with the way .NET handles arguments in cases like these. Remove the arg0 and see what happens.