[IronPython] What C# methods do __repr__ and __str__ use?

[Douglas S. Blank]

Dino Viehland wrote:
> The problem w/ a common __repr__ is that each language will
> presumably have different syntax for creating the object.  For
> example a better repr in Python might be:
> 
> Pixel(255,255,128)
> 
> Where Ruby should probably display something like:
> 
> Pixel.new(255,255,128)

Agreed. But maybe there can be some name *patterns* that if implemented 
once would suffice for most languages. I'm not too worried about this 
though.

> Having a repr of [255,255,128] isn't that meaningful because if I
> copy and paste that into my code I get a list instead of a Pixel
> back.  

Sorry, I switched issues on you :) That was the point of that example... 
generic lists don't look like lists at all. I'm actually more concerned 
with this example than the previous. A generic list of ints, strings, 
etc. ought to be able to have a better representation in IP.

> We could revisit what our default repr does for .NET objects
> that override ToString.  We discussed it once on the list long ago
> but that was mainly focused on dealing w/ multi-line ToStrings if I
> recall correctly - the thought of playing better with multiple
> languages wasn't much of an issue back then for us.
> 
> So basically I am open to suggestions :)

Perhaps generic lists could inherit a version of Python List's __repr__? 
(But of course, not just for Python, but for Ruby, etc.)

Thanks!

-Doug

> -----Original Message----- From: users-bounces at lists.ironpython.com
> [mailto:users-bounces at lists.ironpython.com] On Behalf Of Douglas S.
> Blank Sent: Wednesday, May 28, 2008 1:47 PM To: Discussion of
> IronPython Subject: Re: [IronPython] What C# methods do __repr__ and
> __str__ use?
> 
> Dino Viehland wrote:
>> You'll want to implement the ICodeFormattable interface.  It looks 
>> like we don't pick up a method that's just named __repr__ right
>> now. I could see us fixing that but I wouldn't think it's a high
>> priority unless someone finds implementing ICodeFormattable
>> burdensome.
> 
> Thanks, that did the trick (sample attached below)! It isn't
> burdensome, but I wonder about what will happen when we use IronRuby,
> too? We'll we need repr methods for each language?
> 
> I also wonder if things like a generic list couldn't pick up a 
> reasonable default __repr__ for use in all DLR languages.
> 
> We're using the .NET languages in an educational environment for new 
> students. Currently, we're going to have to add the __repr__ to all 
> classes, and add subclasses to all types for which there isn't a 
> reasonable repr default. For example, there is a pretty big
> difference between: "[255, 255, 128]" and "<List<GraphicsCore+Pixel>
> object at 0x000002C [List<GraphicsCore+Pixel>]>" or whatever it might
> be.
> 
> In any event, we have a work around now; thanks again!
> 
> -Doug
> 
> using System; using IronPython.Runtime; // for ICodeFormattable using
> Microsoft.Scripting.Runtime; // for CodeContext public class TestMe :
> ICodeFormattable { public virtual string __repr__(CodeContext
> context) { return String.Format("<Hi Mom>"); } }
> 
> 
>> -----Original Message----- From: users-bounces at lists.ironpython.com
>>  [mailto:users-bounces at lists.ironpython.com] On Behalf Of Douglas
>> S. Blank Sent: Wednesday, May 28, 2008 12:22 PM To: Discussion of 
>> IronPython Subject: Re: [IronPython] What C# methods do __repr__
>> and __str__ use?
>> 
>> Anyone have an answer for this: I can't write C# code that has its 
>> own method for use in repr(). Am I missing something?
>> 
>> -Doug
>> 
>> Douglas S. Blank wrote:
>>> On Fri, May 23, 2008 3:37 pm, Toni Alatalo said:
>>>> Douglas S. Blank kirjoitti:
>>>>> will use it? Likewise, what C# method is used in Python's 
>>>>> str(obj)?
>>>>> 
>>>> i don't know, but would guess ToString() .. and wonder about it
>>>>  if it wasn't that but something else :o repr() can't guess, i 
>>>> don't think there's an equivalent in .net, but can very well be
>>>>  mistaken there.
>>> It looks like the C# method __str__ is used for the Python
>>> method, but in IP2B2 the C# method __repr__ is getting
>>> overwritten by an auto generated method. Is that a bug, or is
>>> there something I'm missing?
>>> 
>>> $ ipy2 -i python/graphics.py
>>>>>> pm = Pixmap() pm.getPixel(0,0)                    # What is
>>>>>>  this calling?
>>> <Pixel object at 0x2B>
>>>>>> pm.getPixel(0,0).__repr__()         # This is repr() too
>>> '<GraphicsCore+Pixel object at 0x2C [GraphicsCore+Pixel]>'
>>>>>> pm.getPixel(0,0).__Repr__()         # This is mine
>>> '<Pixel at (0,0)>'
>>>>>> pm.getPixel(0,0).__str__()          # That is mine, and
>>>>>> str()
>>>>>> 
>>> '<Pixel at (0,0)>'
>>>>>> pm.getPixel(0,0).ToString()         # Used by __repr__
>>> 'GraphicsCore+Pixel'
>>> 
>>> -Doug
>>> 
>>>>> -Doug
>>>>> 
>>>> ~Toni
>>>> 
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