<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=utf-8">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:Wingdings;
panose-1:5 0 0 0 0 0 0 0 0 0;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.Section1
{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Yes – there is the TypeGen class but really it’s just a thin
wrapper around TypeBuilder w/ some helper APIs. If we were to implement it
today it might just be extension methods instead of a wrapper class.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Unfortunately there is currently no way to go from an expression
tree to an instance method. It’s on the top of the things to fix in the DLR
for a future .NET release. It’s sad that it hasn’t been solved yet but that is
the state of the world. If you really wanted to get crazy you could look at
forking the DLR expression tree compiler and adding support </span><span
style='font-size:11.0pt;font-family:Wingdings;color:#1F497D'>J</span><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>As far as how Python does this – we do generate classes and we
do this via our NewTypeMaker class. But the IL that we create is rather
minimal. We just derive and override every virtual method and have it dispatch
either to the method defined in a PythonType type (which is stored as an
instance field in the object). So while it sucks that we need to generate the
IL by hand it’s small enough that it’s not a big deal.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
users-bounces@lists.ironpython.com [mailto:users-bounces@lists.ironpython.com] <b>On
Behalf Of </b>Justin Chase<br>
<b>Sent:</b> Monday, April 12, 2010 2:03 PM<br>
<b>To:</b> Discussion of IronPython<br>
<b>Subject:</b> Re: [IronPython] Building via AST<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Ok so I'm wondering if I'm perhaps using the wrong words to
try to say what I mean. Because when I look into the IronPython source code I
see a class called Microsoft.Scripting.Generation.TypeGen (<a
href="http://ironpython.codeplex.com/SourceControl/changeset/view/65328#1011039">http://ironpython.codeplex.com/SourceControl/changeset/view/65328#1011039</a>).
Which appears to be code for generating a .net type contrary to your response.
Am I misinterpreting that?<o:p></o:p></p>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Thanks for your examples below but that is about as far as I
have gotten already, what I need is a way to actually generate types and
instances members. And I was just looking at the ILGen class and all it's
interesting helpers but what I'd really love to find is a way to generate this
by just giving it an AST (including "this" references) instead of
having to mess around with IL (hasn't this been solved already??).<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>I know that Python has a "class" construct and
that if I compile scripts I can create instances of these objects, does this
translate into actual .net types under the hood? Or something else? Can you add
attributes or annotations to these classes for example? For my grand finale
what I would really like to do is to generate types that implement interfaces
and load them via MEF (by means of the Export attribute). Is this just the
wrong way to be thinking about this entirely? Or am I just missing something?<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal>On Mon, Apr 12, 2010 at 3:33 PM, Dino Viehland <<a
href="mailto:dinov@microsoft.com">dinov@microsoft.com</a>> wrote:<o:p></o:p></p>
<div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>Nope – the DLR doesn’t have any support
for building .NET types – dynamic or otherwise. If you’d like to just
build an object which behaves dynamically I’d suggest looking at
DynamicObject. You can just subclass it and override various Try* methods
and you’ll have a dynamic object.</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>If you really do need to do ILGen into a
type, and as long as you’re building only static methods, you can use
expression trees via Lambda<T>.CompileToMethod (unfortunately currently
instance methods are not supported). Here’s an example of that:</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>using System;</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>using System.Linq.Expressions;</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>using System.Reflection;</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>class Foo {</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> public static void
Main(string[] args) {</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
var asm = AppDomain.CurrentDomain.DefineDynamicAssembly(new
AssemblyName("foo"),
System.Reflection.Emit.AssemblyBuilderAccess.Save);</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
var module = asm.DefineDynamicModule("foo.dll");</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
var type = module.DefineType("TestType");</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
var param1 = Expression.Parameter(typeof(Foox), "arg1");</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
var param2 = Expression.Parameter(typeof(Foox), "arg2");</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
var method = type.DefineMethod("TestMethod", MethodAttributes.Public
| MethodAttributes.Static);</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
Expression.Lambda<Func<Foox, Foox, bool>>(</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
Expression.Equal(param1, param2),</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
new[] { param1, param2 }</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
).CompileToMethod(method);</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
type.CreateType();</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>
asm.Save("foo.dll");</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> }</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>}</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>enum Foox {</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> Bar,</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> Baz</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'>}</span><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p>
<div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span
style='font-size:10.0pt'>From:</span></b><span style='font-size:10.0pt'> <a
href="mailto:users-bounces@lists.ironpython.com" target="_blank">users-bounces@lists.ironpython.com</a>
[mailto:<a href="mailto:users-bounces@lists.ironpython.com" target="_blank">users-bounces@lists.ironpython.com</a>]
<b>On Behalf Of </b>Justin Chase<br>
<b>Sent:</b> Monday, April 12, 2010 1:21 PM<br>
<b>To:</b> <a href="mailto:users@lists.ironpython.com" target="_blank">users@lists.ironpython.com</a><br>
<b>Subject:</b> [IronPython] Building via AST</span><o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Suppose
I would like to build an AST programmatically and compile that into an assembly
dynamically (meaning an assembly flagged with RunAndCollect) from C#. How would
I do that with IronPython's help? I do not what to author Python code and
compile that I would like to just deal directly with the AST. <o:p></o:p></p>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Currently
I have working code where I'm using System.Linq.Expression namespace to build
statements and expressions into delegates but what I would like is to leverage
the DLR to build dynamic types as well (without having to use ILGenerator
preferably). Is this possible today?<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><br>
-- <br>
Justin Chase <br>
<a href="http://www.justnbusiness.com" target="_blank">http://www.justnbusiness.com</a><o:p></o:p></p>
</div>
</div>
</div>
</div>
</div>
</div>
<p class=MsoNormal style='margin-bottom:12.0pt'><br>
_______________________________________________<br>
Users mailing list<br>
<a href="mailto:Users@lists.ironpython.com">Users@lists.ironpython.com</a><br>
<a href="http://lists.ironpython.com/listinfo.cgi/users-ironpython.com"
target="_blank">http://lists.ironpython.com/listinfo.cgi/users-ironpython.com</a><o:p></o:p></p>
</div>
<p class=MsoNormal><br>
<br clear=all>
<br>
-- <br>
Justin Chase <br>
<a href="http://www.justnbusiness.com">http://www.justnbusiness.com</a><o:p></o:p></p>
</div>
</div>
</div>
</body>
</html>