[IronPython] Writing cross-language libraries that appear native

Jimmy Schementi jschementi at gmail.com
Mon Apr 4 09:54:30 PDT 2011


Tomas means you can write this:

> public static string ExpectsString(string val) {
>        return val;
> }


And call it from Ruby with a Ruby string:

expects_string "Foo"

~Jimmy


On Apr 4, 2011, at 12:21 PM, Doug Blank <doug.blank at gmail.com> wrote:

> On Mon, Apr 4, 2011 at 11:52 AM, Tomas Matousek
> <Tomas.Matousek at microsoft.com> wrote:
>> Re: 1.
>> 
>> MutableString is convertible to String, so why would you need an object parameter?
> 
> Do you mean that one could write:
> 
>    public static string expects_string(MutableString val) {
>        return (val as String);
>    }
> 
> I wrote:
> 
>    public static string expects_string(object val) {
>        return val.ToString();
>    }
> 
> because that would work for all languages, and you could pass in an
> IronPython or F# string it it would work just as well. Or did you mean
> something else?
> 
> -Doug
> 
>> Tomas
>> 
>> -----Original Message-----
>> From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Doug Blank
>> Sent: Monday, April 04, 2011 8:25 AM
>> To: Discussion of IronPython
>> Subject: [IronPython] Writing cross-language libraries that appear native
>> 
>> I'm working on writing C# libraries which can be imported by a variety of .NET languages, DLR and otherwise, which appear native to the language importing them.
>> 
>> For example, writing a C# function that can be used naturally in IronPython as if it were written in Python, IronRuby as if it were written in Ruby, and F# as if it were written in F#, etc.
>> 
>> I've encountered some gotchas that I thought I'd share, and looking for any other points of advice in writing cross-language libraries.
>> 
>> 1. IronRuby strings aren't really strings, so you need to pass them in as an object, and call .ToString().
>> 
>>    public static string expects_string(object val) {
>>        return val.ToString();
>>    }
>> 
>> 2. F# 2.0 doesn't seem to automatically convert a type to the associated nullable type, so avoid nullable types as parameters.
>> 
>>    // AVOID:
>>    public static double? expects_nullable(double? var1=null) {
>>        return var1;
>>    }
>> 
>>    // BETTER:
>>    public static double? expects_nullable() {
>>        return null;
>>    }
>>    public static double expects_nullable(double var1) {
>>        return var1;
>>    }
>> 
>> 3. IronPython and IronRuby lists and dictionaries implement IList and IDictionary, so no problem with those.
>> 
>>    public static IDictionary<object,object> make_dict(object val) {
>>        if (val as IDictionary<object,object> != null) {
>>            return ((IDictionary<object,object>)val);
>>        } else
>>            throw new System.ArgumentException("object is not a dictionary");
>>    }
>> 
>>    public static IList<object> make_list(object val) {
>>        if (val as IList<object> != null) {
>>            return ((IList<object>)val);
>>        } else
>>            throw new System.ArgumentException("object is not a list");
>>    }
>> 
>> Any other suggestions?
>> 
>> -Doug
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>> 
>> 
>> 
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