Ironruby core - Jun 2010 - VB.Net - Ruby interop

Hi,

A couple of technical questions regarding how to leverage Ruby from VB.Net
and vice versa:

1) Is the ScriptScope the only option for passing object refs into Ruby? I
mean can they also be passed as parameters to the Ruby methods called by
InvokeMember?

2) Ruby has no need for passing parameters "ByRef" like you can in VB
because Ruby''s return statement so naturally returns an arbitrary list
of
objects as an array, and Ruby supports multiple assignment on a single line.
But I have legacy VB methods with ByRef parameters that really do change
which objects the parameters reference in the caller. I would like to be
able to call these VB methods from Ruby code, but since Ruby has no such
thing as ByRef, I don''t know what kind of behavior I should expect. Can
the
Ruby variables passed as parameters get reassigned by VB code to point to VB
objects without any additional shenanigans? If not, then is there an
established workaround for ByRef parameters? Has this odd situation been
addressed yet? (I don''t want to rewrite/retest legacy code that already
works just fine).

Thanks,

Julian.
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1)      Yes, you can pass parameters via InvokeMember.

2)      You can call methods with ByRefs from Ruby. An example could be
Dictionary<int, int>.TryGetValue:
>>> dict = System::Collections::Generic::Dictionary[Fixnum, Fixnum].new
=>
System.Collections.Generic.Dictionary`2[System.Int32,System.Int32]
>>> dict.add 1,2
=> nil
>>> dict.try_get_value 1
=> [true, 2]

The second parameter to TryGetvalue is an <Out> ByRef. You can either omit
an argument for such parameter or pass an instance of
System.Runtime.CompilerServices.StrongBox<T>. If you omit the argument the
result is returned in the return value (as shown above). If you pass an instance
of StrongBox the value is updated in situ.

Similarly for in-out ByRef parameters. You pass in the input value and either
get the output value in the resulting array or the StrongBox value if you use a
StrongBox instance.

Tomas


From: ironruby-core-bounces at rubyforge.org [mailto:ironruby-core-bounces at
rubyforge.org] On Behalf Of Julian Bishop
Sent: Sunday, June 06, 2010 10:33 PM
To: ironruby-core at rubyforge.org
Subject: [Ironruby-core] VB.Net - Ruby interop

Hi,

A couple of technical questions regarding how to leverage Ruby from VB.Net and
vice versa:

1) Is the ScriptScope the only option for passing object refs into Ruby? I mean
can they also be passed as parameters to the Ruby methods called by
InvokeMember?

2) Ruby has no need for passing parameters "ByRef" like you can in VB
because Ruby''s return statement so naturally returns an arbitrary list
of objects as an array, and Ruby supports multiple assignment on a single line.
But I have legacy VB methods with ByRef parameters that really do change which
objects the parameters reference in the caller. I would like to be able to call
these VB methods from Ruby code, but since Ruby has no such thing as ByRef, I
don''t know what kind of behavior I should expect. Can the Ruby
variables passed as parameters get reassigned by VB code to point to VB objects
without any additional shenanigans? If not, then is there an established
workaround for ByRef parameters? Has this odd situation been addressed yet? (I
don''t want to rewrite/retest legacy code that already works just fine).

Thanks,

Julian.
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