Help with XDocument in System.Xml.Linq

[taylorzr]

Hello everybody,

I have python experience but I'm new to both cobra and c#. I've trying to write a small application that loads and parses an xml document.

I've written it in python and I've got it working in c# but get an error in cobra:

C#:

Code: Select all

using System.Xml.Linq;

class Program
{
    public static void Main()
    {
        XDocument ticket = XDocument.Load("ticket.xml");
        ...


Cobra:

Code: Select all

use System.Xml.Linq

class Program
    def main
        xml = XDocument.load('ticket.xml')
        ...


Error:

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(empty)(1): error: Cannot implement "Object" which is a class. Use "inherits" in
stead.
Compilation failed - 1 error, 0 warnings
Not running due to errors above.


What am I missing?

-Zach

[Charles]

I can reproduce the problem, but for added information can you tell me your op sys name and version, vm version and Cobra version? I always like to know what people are using, especially when they find a bug.

Sorry this was your first (or early) experience with Cobra. Thanks for reporting it.

[Charles]

Your fix is to explicitly reference the System.Xml library with @ref:

@ref 'System.Xml'

use System.Xml.Linq

class Program
    def main
        xml = XDocument.load('ticket.xml')
        print 'done.'

Or via the command line:

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cobra -c -ref:System.Xml xml.cobra


Obviously, it's a bad user experience to get such a cryptic error message. I'll look into fixing that.

[taylorzr]

OS Version: Windows 7
VM Version: .Net 4.0*
Cobra Version: 0.8

*I'm a little unsure on this. I know I have .Net 4.0 installed. But maybe Cobra is referencing an older version. The MSDN documentation shows XDocument as available in .Net 4.0 & 3.5 only.

When I added the ref to System.Xml I get the error:

Code: Select all

 error: Metadata file "System.Xml.Linq.dll" could not be found

Thanks for the quick response. I'm really excited about this language. I'm an amateur programmer. I've taught myself python for the last ~2 years and I like it. But my company's software deployment consists of Java and .Net and I have no way of deploying python. I like the idea of a 4kb compiled cobra application not a 5mb packaged python application.

So csharp works, but I dislike the syntax and verbosity. Cobra is so much more elegant and flexible. And with built in testing. I might actually write tests

[Charles]

I'm glad you like Cobra.

I experience the same problem on Windows 7 64-bit, even using the latest Cobra from source. I'm looking into it.

[Charles]

Based on the presumption that this was a problem of .NET 2.0 vs. 3.5, I tried this approach and it worked:

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cobra -native-compiler:C:\Windows\Microsoft.NET\Framework\v3.5\csc.exe xml.cobra


There is also a 64-bit version you can try if the above fails you:

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cobra -native-compiler:C:\Windows\Microsoft.NET\Framework64\v3.5\csc.exe xml.cobra


If your "cobra" command in your PATH is a .bat or .cmd file, you can enhance it to pass the -native-compiler option down to cobra.exe so you don't have to do this every time.

My current code is then:

@ref 'System.Xml'

use System.Xml
use System.Xml.Linq

class Program

    def main
        xml = XDocument.load('ticket.xml')
        trace xml

[taylorzr]

Awesome. Thanks for your help. Compiles and runs as expected now.

I modified the .bat from:

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@"C:\Cobra\Cobra-0.8.0-post\bin\cobra.exe" %*


to:

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@"C:\Cobra\Cobra-0.8.0-post\bin\cobra.exe" -native-compiler:C:\Windows\Microsoft.NET\Framework\v3.5\csc.exe %*