Comments on: DictMixin http://blog.ianbicking.org/2007/08/17/dictmixin/ Wed, 08 Sep 2010 10:58:09 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Ian Bicking http://blog.ianbicking.org/2007/08/17/dictmixin/comment-page-1/#comment-193 Ian Bicking Fri, 17 Aug 2007 18:40:42 +0000 http://blog.ianbicking.org/2007/08/17/dictmixin/#comment-193 I'm not exactly sure what you were doing. `obj.__dict__` must be a real dictionary, I don't even think a dictionary subclass is okay. But that's right at the heart of Python's objects, so it's not too surprising -- lots of low-level code pokes right into an instance's dictionary structure directly, I imagine. I'm *guessing* something along those lines is what happened to you with Storm? There's also questions like "can this object change behind my back?" -- which you can feel more confident about with a real dictionary. As an example, WSGI doesn't allow dictionary-like objects for requests, only exactly `dict`. It's like a contract in that case. You can do `class Foo(object, DictMixin):` if you want a new-style dict-like class; that works fine. I’m not exactly sure what you were doing. obj.__dict__ must be a real dictionary, I don’t even think a dictionary subclass is okay. But that’s right at the heart of Python’s objects, so it’s not too surprising — lots of low-level code pokes right into an instance’s dictionary structure directly, I imagine. I’m guessing something along those lines is what happened to you with Storm? There’s also questions like “can this object change behind my back?” — which you can feel more confident about with a real dictionary. As an example, WSGI doesn’t allow dictionary-like objects for requests, only exactly dict. It’s like a contract in that case.

You can do class Foo(object, DictMixin): if you want a new-style dict-like class; that works fine.

]]> By: Jim http://blog.ianbicking.org/2007/08/17/dictmixin/comment-page-1/#comment-190 Jim Fri, 17 Aug 2007 11:45:03 +0000 http://blog.ianbicking.org/2007/08/17/dictmixin/#comment-190 DictMixin is handy. But it's an old-style class, and I ran into difficulty when using it to store dictionary contents in a database with Storm because of that. This led me to the #storm IRC channel, where I was told simply that what I was doing wasn't a proper dictionary and therefore I should use an over-complicated delegation system instead. Ugh. I can't see the point of that. Yes, a class using DictMixin can do some clever stuff behind the scenes that you wouldn't necessarily expect from a normal dictionary. But that doesn't mean that it isn't actually a dictionary, does it? It still stores key/value pairs, right? I think adapting simple interfaces like the Dict interface to complex behaviour is one of the things that makes Python so useful. I don't see the problem with "magic" like this, in fact I think it's a great thing. What do you say to people who want to double your class-count for the sake of it? Telling them to go back to Java sounds too snotty, but their attitude isn't great either. DictMixin is handy. But it’s an old-style class, and I ran into difficulty when using it to store dictionary contents in a database with Storm because of that. This led me to the #storm IRC channel, where I was told simply that what I was doing wasn’t a proper dictionary and therefore I should use an over-complicated delegation system instead. Ugh.

I can’t see the point of that. Yes, a class using DictMixin can do some clever stuff behind the scenes that you wouldn’t necessarily expect from a normal dictionary. But that doesn’t mean that it isn’t actually a dictionary, does it? It still stores key/value pairs, right?

I think adapting simple interfaces like the Dict interface to complex behaviour is one of the things that makes Python so useful. I don’t see the problem with “magic” like this, in fact I think it’s a great thing. What do you say to people who want to double your class-count for the sake of it? Telling them to go back to Java sounds too snotty, but their attitude isn’t great either.

]]> By: Michael Neumann http://blog.ianbicking.org/2007/08/17/dictmixin/comment-page-1/#comment-189 Michael Neumann Fri, 17 Aug 2007 08:32:38 +0000 http://blog.ianbicking.org/2007/08/17/dictmixin/#comment-189 I wrote a Ruby version of your FSDict class. It's here: http://blog.ntecs.de/articles/2007/08/17/ian-bickings-fsdict-in-ruby I wrote a Ruby version of your FSDict class. It’s here: http://blog.ntecs.de/articles/2007/08/17/ian-bickings-fsdict-in-ruby

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