I’m trying to pass a COM object from C# code to Perl.
At the moment I’m wrapping my Perl code with PerlNET (PDK 9.4; ActiveState) and I have defined a simple subroutine (+ required pod declaration) in Perl to pass objects from C# to the wrapped Perl module.
It seems that the objects I pass are not recognized correctly as COM objects.
An example:
In C# (.NET 4.0), the ScriptControl is used to load a simple class from a file written in VBScript.
var host = new ScriptControl();
host.Language = "VBScript";
var text = File.ReadAllText("TestScript.vbs");
host.AddCode(text);
dynamic obj = host.Run("GetTestClass");
What I get (obj) is of type System.__ComObject. When I pass it to my Perl/PerlNET assembly and try to call method Xyz() in Perl I get the following (runtime) exception:
Can't locate public method Xyz() for System.__ComObject
If, however, I do more or less the same thing in Perl, it works. (In the following case, passing only the contents of my .vbs file as parameter.)
I can even use the script control :
sub UseScriptControl {
my ($self, $text) = #_;
my $script = Win32::OLE->new('ScriptControl');
$script->{Language} = 'VBScript';
$script->AddCode($text);
my $obj = $script->Run('GetTestClass');
$obj->Xyz();
}
Now, calling Xyz() on obj works fine (using Win32::OLE).
In both cases I use:
use strict;
use Win32;
use Win32::OLE::Variant;
Another approach:
I can invoke methods by using InvokeMember of class System.Type if I specify exactly which overload I want to use and which types I’m passing:
use PerlNET qw(typeof);
typeof($obj)->InvokeMember("Xyz",
PerlNET::enum("System.Reflection.BindingFlags.InvokeMethod"),
PerlNET::null("System.Reflection.Binder"),
$obj,
"System.Object[]"->new());
Using this approach would mean rewriting the whole wrapped Perl module. And using this syntax..
Now I am wondering if I am losing both the advantages of the dynamic keyword in .NET 4.0 and the dynamic characteristics of Perl (with Win32::OLE) by using PerlNET with COM objects.
It seems like my preferred solution boils down to some way of mimicking the behaviour of the dynamic keyword in C#/.NET 4.0.
Or, better, finding some way of converting the passed COM object to something that will be recognized as compatible with Win32::OLE. Maybe extract some information of the __ComObject for it to be identified correctly as COM object.
I have to add that I posted to the PDK discussion site too (but didn’t get any response yet): http://community.activestate.com/node/18247
I also posted it to PerlMonks - as I'm not quite sure if this is more a Perl or C#/.NET question:
http://www.perlmonks.org/?node_id=1146244
I would greatly appreciate any help - or advise on where to look further.
Related
Can someone give me an example of the use of the RunCommand method that takes a string argument only (called CommandName) available in the MongoDB .NET driver? I know there is an overloaded RunCommand method that takes an object reference (I think a CommandDocument object) as an argument, but I'd rather not use that one.
I'm having trouble getting the syntax right for CommandName. Thanks in advance!
If you are using some recent version of the official C# driver, the "real" string based version you are referring to (CommandResult RunCommand(string commandName)) is only part of the legacy driver component (check the namespace). I would hence not recommend using it.
The "official" interface currently looks like this:
TResult RunCommand<TResult>(Command<TResult> command, /* and some additional optional parameters */)
And since the C# driver heavily relies on implicit type conversions, there also is one from a string (and a BsonDocument) to the corresponding sub types of Command<TResult> (JsonCommand<TResult> and BsonDocumentCommand<TResult>). So you can effectively pass a string to the above new RunCommand() method, too.
You can therefore write either one of the following lines both of which do the exact same thing:
RunCommand<BsonDocument>("{count: \"collection_name\"}")
RunCommand<BsonDocument>(new BsonDocument("count", "collection_name"))
I am writing a scripting engine for my game using the LuaInterface library. I am getting an error when attempting to instantiate the class in Lua. The error is:
"./Scripts/sv_worldgen.lua:2: attempt to call global 'Campfire' (a string value)"
Where sv_worldgen.lua is (in entirety):
function GenerateChunk(worldChunk, chunkGridPosition)
tf = Campfire()
tf:SetPosition(chunkGridPosition)
end
Campfire is a class in C#, and appears to be exposed to lua as per the CLRPackage example and of course the LuaInterface Reference. I cannot seem to get around this error, and I have done due diligence of searching. The only other behavior of the script I can manage throws a similar error, but where it is "(a table value)". What am I doing wrong? Thank you in advance!
I tried explicitly doing Campfire._ctor(), but _ctor() is a string value.
This was resolved by using CLRPackage and using it to first load the assembly.
//Lua
JASG = CLRPackage("JASG", "JASG")
Then and only then can you link the classname to the actual C# class using (this must be done before trying to access it in Lua):
//Lua
Campfire=JASG.Campfire;
and then normal instantiation can occur by
//Lua
cf = Campfire()
I have some old VB code to send mails using Lotus Notes that works, I have re-written it into C#, but it behaves differently:
VB:
NotesSession = CreateObject("Notes.Notessession")
NotesDb = NotesSession.GetDatabase("", "")
C#:
_notesSession = new NotesSession();
_notesSession.Initialize(passwordString);
_notesDatabase = _notesSession.GetDatabase( "", "");
First of in C# I need to Initialize the NotesSession with a password, and secondly it will not accept empty string parameters at runtime. Exception is thrown: "A database name must be provided".
In both VB and C# I refer to the same COM : Lotus Domino Objects
I need to be able to call the GetDatabase without specifying the server and database file.
Thanks in advance.
Solution (Thanks guys):
dynamic _notesSession = Activator.CreateInstance(Type.GetTypeFromProgID("Notes.NotesSession"));
_notesDatabase = _notesSession.GetDatabase("", "");
This way you have no intellisense but all properties and methods can be found here
When you create a new instance of the NoteSession type in C# using the new keyword, it will use the COM-interop dll that was referenced by the project at build-time. That is not exactly the same thing as calling CreateObject, which requires no interop dll. The closer equivalent in C# would be:
Type t = Type.GetTypeFromProgID("Notes.Notessession");
_notesSession = Activator.CreateInstance(t);
Or, if you really need to do the exact same thing, you could always add a reference to the Microsoft.VisualBasic.dll library and then call the Microsoft.VisualBasic.Interaction.CreateObject method from C#.
As Richard pointed out in the comments below, the likely reason why you are seeing a difference in behavior is because you are creating two different types of objects. Presumably, when you call new NotesSession in C#, it is using the NotesSession class from the Lotus namespace, rather than the one in the Notes namespace.
I'm using IronRuby and trying to work out how to use a block with a C# method.
This is the basic Ruby code I'm attempting to emulate:
def BlockTest ()
result = yield("hello")
puts result
end
BlockTest { |x| x + " world" }
My attempt to do the same thing with C# and IronRuby is:
string scriptText = "csharp.BlockTest { |arg| arg + 'world'}\n";
ScriptEngine scriptEngine = Ruby.CreateEngine();
ScriptScope scriptScope = scriptEngine.CreateScope();
scriptScope.SetVariable("csharp", new BlockTestClass());
scriptEngine.Execute(scriptText, scriptScope);
The BlockTestClass is:
public class BlockTestClass
{
public void BlockTest(Func<string, string> block)
{
Console.WriteLine(block("hello "));
}
}
When I run the C# code I get an exception of:
wrong number of arguments (0 for 1)
If I change the IronRuby script to the following it works.
string scriptText = "csharp.BlockTest lambda { |arg| arg + 'world'}\n";
But how do I get it to work with the original IronRuby script so that it's the equivalent of my original Ruby example?
string scriptText = "csharp.BlockTest { |arg| arg + 'world'}\n";
Ruby's blocks are not a concept understood by c# (or any of the other .Net languages).
To 'pass one' to the similar concept in c# of the delegate you must 'wrap it' in something that is understandable.
By making a lambda out of the block it becomes something you can pass to c# code expecting a delegate or expression.
This is a common issue with the 'Alt.Net' community, even for blessed languages like f# where 'functions pointers' are not implemented as delegates but instead are done slightly differently (FastFunc instances in f# for example) to pass one of these to something like your c# example would require wrapping it in a delegate (literally creating a delegate whose invocation passes the parameters to the underlying instance and returns the result back).
One could argue that such translation would be nicer if it was automatic, but doing that can lead to complex and strange edge cases or bugs and many developers prefer to know that such a wrapping operation will occurred just by looking at the code. It is also the case that there may not always be reasonable conversion (or more than one exists) so making the user decide what happens is a sensible default.
For the most part, IronRuby Procs and lambdas are interchangeable with CLR Actions, Funcs, delegate types, and dynamic objects. However there's little Ruby syntactic sugar over this, other than some call-site conversions. Once place we did sweeten up the syntax was for .NET events; IronRuby allows passing a Ruby block as an CLR event handler: button.on_click {|s,e| ... }.
We have toyed a bunch of ways to allow blocks to be passed to CLR methods; either by detecting methods whose last argument is a callable object, or by allowing a special named parameter. There's a feature request (though cryptically named) already open for this: http://ironruby.codeplex.com/workitem/4511. Would be a good challenge for anyone willing to contribute.
You can totally use ruby blocks in c#, in fact i have used this in an application that is currently in production! here is how:
In c# file:
public void BlockTest(dynamic block)
{
Console.WriteLine(block.call("world"));
}
In Ironruby:
#require the assembly
block = Proc.new {|i| "hello " + i }
Blah::Blah.BlockTest block
note: tested in c# 4.0 only
I have inherited a small scripting language and I am attempting to port it to the DLR so that it is a little easier to manage. So far it has been fairly straight forward. I have run into a problem though attempting to dynamically call members of a variable. The current language runs on .NET and uses a parsing loop and reflection to do this, but I was hoping to get away from that. Here is an example of the script language:
string $system1RemoteUri;
string $dbconnection = $config.GetDBConnection ("somedb");
float $minBad = 0.998;
float $minGood = 0.2;
$systen1RemoteURI, $minBad, and $minGood are variables that will be set in the script, along with $dbconnection. However $dbconnection will get its value from a variable passed in called $config. The 4 variables need to be available to the caller, so they are passed into the lambda, initially as null. Here is the generated Lambda IL (debug view):
.Lambda #Lambda1<Delegate6$1>(
System.String& $$system1RemoteUri,
System.String& $$dbconnection,
System.Double& $$minBad,
System.Double& $$minGood
System.Object $$config) {
.Block() {
$$minBad = 0.998D;
$$minGood = 0.2D
}
//Some assignment similar to...
//.Dynamic Call GetDBConnection($config, "somedb");
}
What I am trying to figure out is how to use Expression.Dynamic to emit the $config.GetDBConnection("somedb"). From looking at examples in the Sympl libraries I believe the emitted IL should look like:
.Dynamic Call GetdbConnection($config, "somedb") but I cant figure out how to actually emit that from Expression.Dynamic.
It seems to want a CallSiteBinder which I cannot create correctly, and I do not understand what the order of parameters is to Expression.Dynamic, as it seems to only want the "member" being invoked, and not the base.
I do not know the runtime type of $config it is just some object which implements a function called GetDBConnection(string). This is not provided by an interface or base class.
Any help would be appreciated.
You can either turn this into an InvokeMemberBinder or turn "$config.GetDBConnection" into a GetMember and then do an Invoke on the result of that passing $someDb as the argument.
To implement your GetMemberBinder and InvokeMemberBinder you can use the DLR outer-layer DefaultBinder class. In the latest IronPython/IronRuby source code you can just create a new DefaultBinder instance out of thin air. Then in your FallbackGetMember / FallbackInvoke you can call defaultBinder.GetMember(...) and defaultBinder.Call (which should be renamed Invoke). That'll deal with most .NET types for you. Also all objects which implement IDynamicMetaObjectProvider will work with it as well. For other dynamic operations you can use the other methods on the default binder. And if you want to start customizing your overload resolution and binding rules it has lots of knobs you can turn.
Unfortunately the default binder doesn't have an InvokeMemberBinder implementation right now so you're probably better off w/ GetMember/Invoke.