Iron Python: the output stream.
I needed to embed IronPython in my Second Messenger project. So i wrote a small interactive console looking like this:
where in the upper section i write my code and sending the output stream on the bottom section.
So i wrote the following class:
class MyPythonStream : Stream
{
#region unsupported Read + Seek members
public override bool CanRead
{
get { return false; }
}
public override bool CanSeek
{
get { return false; }
}
public override bool CanWrite
{
get { return true; }
}
public override void Flush()
{
// ...
}
public override long Length
{
get { throw new NotSupportedException("Seek not supported"); } // can't seek
}
public override long Position
{
get
{
throw new NotSupportedException("Seek not supported"); // can't seek
}
set
{
throw new NotSupportedException("Seek not supported"); // can't seek
}
}
public override int Read(byte[] buffer, int offset, int count)
{
throw new NotSupportedException("Reed not supported"); // can't read
}
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException("Seek not supported"); // can't seek
}
public override void SetLength(long value)
{
throw new NotSupportedException("Seek not supported"); // can't seek
}
#endregion
public override void Write(byte[] buffer, int offset, int count)
{
// Very bad hack: Ignore single newline char. This is because we expect the newline is following
// previous content and we already placed a newline on that.
if (count == 1 && buffer[offset] == '\n')
return;
// Code update from ShawnFa to fix case for '\r'
StringBuilder sb = new StringBuilder();
while (count > 0)
{
char ch = (char)buffer[offset]; if (ch == '\n')
{
OnWrite(sb.ToString());
sb.Length = 0; // reset.
}
else if (ch != '\r')
{
sb.Append(ch);
}
offset++;
count--;
}
// Dump remainder. @todo - need some sort of "Write" to avoid adding extra newline.
if (sb.Length > 0)
OnWrite(sb.ToString());
}
public delegate void OnWriteCallback(string s);
public OnWriteCallback OnWrite;
}
This class allows you to add your own custom OnWriteCallback according to the delegate definition: public delegate void OnWriteCallback(string s);
I finally added an instance of the class to my code:
PythonEngine engine; MyPythonStream myOut; // Creating the engine engine = new PythonEngine( ); // Creating the stream myOut = new MyPythonStream(); myOut.OnWrite = new MyPythonStream.OnWriteCallback(Python_OnWrite); // Setting the output streams engine.SetStandardOutput(myOut); engine.SetStandardError(myOut);
where my callback looks like:
public void Python_OnWrite(string s) {
this.textview2.Buffer.Text += s +"\n"; // Gtk# textview output
}
Now I can write my python code:
a = [ 'a', 123, 5.0 ]
for x in a:
print x
and executing it:
