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pythonnet@python.org

February 2022

3 participants
2 discussions

Binding to a DynamicObject
by Taylor, Guy 22 Feb '22

22 Feb '22

Hi there, I'm new to the list, and fairly new to python integration with C#, so I was hoping someone could help me. I am trying to bind a c# class (which is derived DynamicObject) to Pythonnet but can't get the dynamic aspect working. In the following Code, the line : AppBind.Description("layout") works fine and calls the C# method: public void Description(string str) But AppBind.DynMethod(123) throws an error stating the method doesn't exist (I was hoping this would be called: public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) And AppBind.Fred = 123 Assigns 123 to a python variable Fred, when I was hoping it would call: public override bool TrySetMember(SetMemberBinder binder, object value) Is there a way to make this work? The closest I've found is this page, but I couldn't work it out: https://github.com/pythonnet/pythonnet/issues/72 Thank you Guy Here is the python snippet: AppBind = PythonSpace.PythonCallbacks() def DoStuff(): AppBind.Description("layout") AppBind.DynMethod(123) AppBind.Fred = 123 Here is the C# code: (This is derived from the the DynamicDictionary example ) public class PythonCallbacks : System.Dynamic.DynamicObject { // The inner dictionary. Dictionary<string, object> dictionary = new Dictionary<string, object>(); public void Description(string str) { } public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { return base.TryInvokeMember(binder, args, out result); } // If you try to get a value of a property // not defined in the class, this method is called. public override bool TryGetMember(GetMemberBinder binder, out object result) { // Converting the property name to lowercase // so that property names become case-insensitive. string name = binder.Name.ToLower(); // If the property name is found in a dictionary, // set the result parameter to the property value and return true. // Otherwise, return false. return dictionary.TryGetValue(name, out result); } // If you try to set a value of a property that is // not defined in the class, this method is called. public override bool TrySetMember(SetMemberBinder binder, object value) { // Converting the property name to lowercase // so that property names become case-insensitive. dictionary[binder.Name.ToLower()] = value; // You can always add a value to a dictionary, // so this method always returns true. return true; } } }

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Stricter types in 3.0
by Felix Bourbonnais 03 Feb '22

03 Feb '22

Hello, as was discussed in the bi-weekly meeting, the newest version seems to introduce stricter type checking. Here's a snippet that exhibits two issues. using (Py.GIL()) { dynamic sysmod = Py.Import("sys"); dynamic syspath = sysmod.path; bool found = false; foreach (var path in syspath) { if (path == Path.GetFullPath("some/test/path/").Replace("\\", "/")) { found = true; break; } } } The first is a runtime exception with syspath: Microsoft.CSharp.RuntimeBinder.RuntimeBinderException : Cannot implicitly convert type 'Python.Runtime.PyObject' to 'System.Collections.IEnumerable'. An explicit conversion exists (are you missing a cast?) The second is maybe a non-issue, but I think it used to work. If syspath is made to be of type PyList there is now a compiler error: error CS0019: Operator '==' cannot be applied to operands of type 'PyObject' and 'string' Thanks

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