Comments on: An Identity Mapper in Django (formerly Django Singletons) http://www.davidcramer.net/code/375/singletons-in-django.html A blog about Django, JavaScript, CSS, and general web development. Fri, 12 Mar 2010 19:46:01 -0600 http://wordpress.org/?v=2.9.2 hourly 1 By: Tom. http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20529 Tom. Tue, 02 Dec 2008 23:47:29 +0000 http://www.davidcramer.net/?p=375#comment-20529 This sounds wicked! Thanks. This sounds wicked! Thanks.

]]> By: dailycad http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20527 dailycad Tue, 02 Dec 2008 21:45:07 +0000 http://www.davidcramer.net/?p=375#comment-20527 Very useful info.. Thanks.. Very useful info.. Thanks..

]]> By: David Cramer http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20526 David Cramer Tue, 02 Dec 2008 20:21:50 +0000 http://www.davidcramer.net/?p=375#comment-20526 Ah if you are correct then I will be renaming the project. I haven't done much research (in terminology), but had assumed it was correct via the ticket on Django. Ah if you are correct then I will be renaming the project. I haven't done much research (in terminology), but had assumed it was correct via the ticket on Django.

]]> By: Steingrim http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20524 Steingrim Tue, 02 Dec 2008 20:10:37 +0000 http://www.davidcramer.net/?p=375#comment-20524 I think calling this Singletons is quite misleading. The Singleton Pattern is used to enforce a single instance of a class; not a single instance of a business entity. Identity Map is the correct naming but note Fowler's emphasis on using one Identity Map per transaction. I think calling this Singletons is quite misleading. The Singleton Pattern is used to enforce a single instance of a class; not a single instance of a business entity. Identity Map is the correct naming but note Fowler's emphasis on using one Identity Map per transaction.

]]> By: David Cramer http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20523 David Cramer Tue, 02 Dec 2008 19:34:51 +0000 http://www.davidcramer.net/?p=375#comment-20523 Personally, I plan to use it throughout the codebase to prevent some data issues. The one area this doesn't affect right now (due to complications we had with it at Curse) is serialization. It will ignore the instance caching when you unserialize objects (such as from the cache). Personally, I plan to use it throughout the codebase to prevent some data issues. The one area this doesn't affect right now (due to complications we had with it at Curse) is serialization. It will ignore the instance caching when you unserialize objects (such as from the cache).

]]> By: David Cramer http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20522 David Cramer Tue, 02 Dec 2008 19:31:28 +0000 http://www.davidcramer.net/?p=375#comment-20522 I think per query is a bit out of scope for what I want to achieve. Doing this would require the queryset/manager to be aware (to some extent) of the singleton model. This wouldn't quite achieve the same performance benefit.<br><br>The biggest thing about this, while it IS an obvious performance boost, its not the sole intention of the project. Having unique instances of an object in memory can solve a lot of other issues as well. I think per query is a bit out of scope for what I want to achieve. Doing this would require the queryset/manager to be aware (to some extent) of the singleton model. This wouldn't quite achieve the same performance benefit.

The biggest thing about this, while it IS an obvious performance boost, its not the sole intention of the project. Having unique instances of an object in memory can solve a lot of other issues as well.

]]> By: Sam Toriel http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20521 Sam Toriel Tue, 02 Dec 2008 16:45:27 +0000 http://www.davidcramer.net/?p=375#comment-20521 ^^ My questions exactly ^^ My questions exactly

]]> By: Rob Hudson http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20520 Rob Hudson Tue, 02 Dec 2008 16:42:49 +0000 http://www.davidcramer.net/?p=375#comment-20520 Could there be a way to enable this per query? In your example, it's obvious that creating only one instance per category is optimal, but are there cases where it may not be what you want? Could there be a way to enable this per query? In your example, it's obvious that creating only one instance per category is optimal, but are there cases where it may not be what you want?

]]> By: tcdavis http://www.davidcramer.net/code/375/singletons-in-django.html/comment-page-1#comment-20518 tcdavis Tue, 02 Dec 2008 14:21:24 +0000 http://www.davidcramer.net/?p=375#comment-20518 So, two questions.<br><br>1. Per your explanation, it wasn't strictly necessary to define Article as a SingleModel, correct?<br><br>2. Given the obvious benefits, are there any reasons not to use this class for all models? Am I missing something crucial here? So, two questions.

1. Per your explanation, it wasn't strictly necessary to define Article as a SingleModel, correct?

2. Given the obvious benefits, are there any reasons not to use this class for all models? Am I missing something crucial here?

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