File Opened in Python not passed as FileStream

Environment

• Pythonnet version: 2.4.0.dev0
• Python version: 3.7.1:260ec2c36a
• Operating System: MSC v.1915 64 bit (AMD64)

Details

• Pass a python opened file to a referenced constructor that takes a Stream as a parameter.

The library used was DiscUtils 0.11.0.0

import os, sys, clr
clr.AddReference("DiscUtils")
import DiscUtils.Iso9660 as Iso9660

def readUdf(path):
    with open(path, 'rb') as file: # modes 'r', 'rb' and their + varients all fail
        reader = Iso9660.CDReader(file, False)

• If there was a crash, please include the traceback here.

Traceback (most recent call last):
  File "-snip path-\main.py", line 100, in <module>
    if args.read is not None: readUdf(args.read)
  File "-snip path-\main.py", line 19, in readUdf
    reader = Iso9660.CDReader(file, False)
TypeError: no constructor matches given arguments

I initially got around it by writing a small dll that would have a constructor that would take a string as it's only arguments and then return a new CDReader object. After learning a bit of C# while doing so I later discovered after playing around that the following code would work without issue.

clr.AddReference("DiscUtils")
import DiscUtils.Iso9660 as Iso9660
from System.IO import FileStream, FileMode, FileAccess

def readUdf(path):
    file = FileStream(path, FileMode.Open, FileAccess.Read)
    reader = Iso9660.CDReader(file, False)

I'm not entirely sure if this is actually an issue or not but I would have thought that passing it as a python opened file object would pass it as a FileStream.

[filmor]

The reason for that is that Python file objects and .NET FileStream objects may implement the same "thing", but they are entirely independent and incompatible implementations. This is not an issue of Python.NET, you'd see the same thing if you had two different Stream APIs within the same language, like FILE* and std::fstream in C++.

If you need to use Python objects for the actual files, you'd have have to implement your own C#-class that inherits from System.IO.Stream and wraps a PyObject that is itself a stream. Performance-wise, I wouldn't recommend this and instead stick with the solution you have found.