Ironruby core - Feb 2009 - setting global variables in embedded ironruby interpreter

Hello,

I am very pleased that I got everything working and found iron ruby in a
quite usable state for me. Congratulations.

Question: How do you set a global variable from C#? I found a workaround via
setting a local variable scope.SetVariable("a", obj) in the scope and
assigning it to a global via engine.Execute("$a=a", scope).
The Runtime.Globals.GetVariable and SetVariable don''t seem to get / set
the
ruby globals.
Please clarify.

BTW: as for local variables: scope.GetVariableNames() does return an empty
list. Again a workaround is Execute("local_variables", scope).
-- henon
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On Mon, Feb 9, 2009 at 12:12 PM, Meinrad Recheis
<meinrad.recheis at gmail.com>wrote:
> Hello,
>
> I am very pleased that I got everything working and found iron ruby in a
> quite usable state for me. Congratulations.
>
> Question: How do you set a global variable from C#? I found a workaround
> via setting a local variable scope.SetVariable("a", obj) in the
scope and
> assigning it to a global via engine.Execute("$a=a", scope).
> The Runtime.Globals.GetVariable and SetVariable don''t seem to get
/ set the
> ruby globals.
>
Oh, i just found out that ScriptScope.GetVariable is throwing an exception
...

********************************************************************************
ArgumentNullException: "Value cannot be null.
Parameter name: field"
--------------------------------------------------------------------------------
  Microsoft.Scripting.Utils.ContractUtils.RequiresNotNull(Object value,
String paramName)
  Microsoft.Scripting.SymbolTable.StringToId(String field)
  Microsoft.Scripting.Hosting.ScriptScope.GetVariable(String name)
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On Mon, Feb 9, 2009 at 1:05 PM, Meinrad Recheis
<meinrad.recheis at gmail.com>wrote:
> On Mon, Feb 9, 2009 at 12:12 PM, Meinrad Recheis <
> meinrad.recheis at gmail.com> wrote:
>
>> Hello,
>>
>> I am very pleased that I got everything working and found iron ruby in
a
>> quite usable state for me. Congratulations.
>>
>> Question: How do you set a global variable from C#? I found a
workaround
>> via setting a local variable scope.SetVariable("a", obj) in
the scope and
>> assigning it to a global via engine.Execute("$a=a", scope).
>> The Runtime.Globals.GetVariable and SetVariable don''t seem to
get / set
>> the ruby globals.
>>
>
> Oh, i just found out that ScriptScope.GetVariable is throwing an exception
> ...
>
>
>
********************************************************************************
> ArgumentNullException: "Value cannot be null.
> Parameter name: field"
>
>
--------------------------------------------------------------------------------
>   Microsoft.Scripting.Utils.ContractUtils.RequiresNotNull(Object value,
> String paramName)
>   Microsoft.Scripting.SymbolTable.StringToId(String field)
>   Microsoft.Scripting.Hosting.ScriptScope.GetVariable(String name)
>
sorry forgot to say, that I made sure, that the "name" parameter is
*not*
null.
I am not yet deep enough into the sources to fix things like these myself.

-- henon
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On Mon, Feb 9, 2009 at 1:11 PM, Meinrad Recheis
<meinrad.recheis at gmail.com>wrote:
> On Mon, Feb 9, 2009 at 1:05 PM, Meinrad Recheis <meinrad.recheis at
gmail.com
> > wrote:
>
>> On Mon, Feb 9, 2009 at 12:12 PM, Meinrad Recheis <
>> meinrad.recheis at gmail.com> wrote:
>>
>>> Hello,
>>>
>>> I am very pleased that I got everything working and found iron ruby
in a
>>> quite usable state for me. Congratulations.
>>>
>>> Question: How do you set a global variable from C#? I found a
workaround
>>> via setting a local variable scope.SetVariable("a", obj)
in the scope and
>>> assigning it to a global via engine.Execute("$a=a",
scope).
>>> The Runtime.Globals.GetVariable and SetVariable don''t seem
to get / set
>>> the ruby globals.
>>>
>>
>> Oh, i just found out that ScriptScope.GetVariable is throwing an
exception
>> ...
>>
>>
>>
********************************************************************************
>> ArgumentNullException: "Value cannot be null.
>> Parameter name: field"
>>
>>
--------------------------------------------------------------------------------
>>   Microsoft.Scripting.Utils.ContractUtils.RequiresNotNull(Object value,
>> String paramName)
>>   Microsoft.Scripting.SymbolTable.StringToId(String field)
>>   Microsoft.Scripting.Hosting.ScriptScope.GetVariable(String name)
>>
>
> sorry forgot to say, that I made sure, that the "name" parameter
is *not*
> null.
> I am not yet deep enough into the sources to fix things like these myself.
>
> -- henon

ok, I was too fast on this one. actually it was null because a ruby_string
casted to c# string is null. It is pretty dangerous to assume a value
presented as "a" by the debugger to be a System.String when that value
comes
out from ruby ;)

so the problem is not the exception but rather that GetVariable("a")
does
not find existing local variables which can be evaluated by
Execute("a").
This time I made sure I made no mistake.
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You can find many hosting examples in HostingTests.cs.

As for global and top-level local variables:

-          Variables in ScriptRuntimeRuntime.Globals are mapped to global
constants (ie. constants on Object).

-          Variables in local ScriptScope are not mapped to Ruby top-level local
variables. They are looked up via method_missing on a top-level singleton
object. Ruby top-level program executes in a context where "self" is a
singleton of Object. IronRuby defines method_missing on this singleton. If a
method name ends with "=" it writes to the scope, otherwise it reads
from the scope.

ScriptScope scope = Engine.CreateScope();
scope.SetVariable("x", 1);
scope.SetVariable("y", 2);
Engine.Execute("self.z = x + y", scope);
int result = scope.GetVariable<int>("result");
Assert(result == 3);

Ruby global variables don''t have any mapping to DLR scopes. We
don''t have any well designed API for them yet, you can do this for now:

Ruby.GetExecutionContext(Engine).DefineGlobalVariable("foo", 123);

Tomas

From: ironruby-core-bounces at rubyforge.org [mailto:ironruby-core-bounces at
rubyforge.org] On Behalf Of Meinrad Recheis
Sent: Monday, February 09, 2009 3:13 AM
To: ironruby-core
Subject: [Ironruby-core] setting global variables in embedded ironruby
interpreter

Hello,

I am very pleased that I got everything working and found iron ruby in a quite
usable state for me. Congratulations.

Question: How do you set a global variable from C#? I found a workaround via
setting a local variable scope.SetVariable("a", obj) in the scope and
assigning it to a global via engine.Execute("$a=a", scope).
The Runtime.Globals.GetVariable and SetVariable don''t seem to get / set
the ruby globals.
Please clarify.

BTW: as for local variables: scope.GetVariableNames() does return an empty list.
Again a workaround is Execute("local_variables", scope).
-- henon
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