Bruno, exactly what I've been looking for! Thanks!
On Jun 4, 11:28 am, bruno desthuilliers <bruno.desthuilli...@gmail.com> wrote: > On Jun 3, 12:18 pm, mikegolf <miga...@gmail.com> wrote: > > > Hi, > > I've started to learn Django recently, however for last 5+ years I've > > been developing using PHP (especially Yii) and thus asking if there's > > any tutorial / documentation on significant differences in > > *thinking*. > > What I mean is for example objects' lifecycle - for PHP the life cycle > > of object is strictly related to the single request.. > > I know that for Python / Django developers these are obvious things, > > but not for me. Thus I'd love to see an article / document which > > points these base and significant differences. > > Any recommendations? > > Well, the answer may not be as simple as it seems, as it first > requires a correct understanding of Python's execution model, > namespaces, scopes and bindings (aka "variables") - and this would > make for a rather long and technical document. Then you have to know > how your django application is deployed. > > I think the most important points wrt/ "objects lifcycle" are (overly > simplified): > > * a Python module's top-level code is executed once the first time the > module is imported > * "import", "class" and "function" statements are executable > statements > * the code at the toplevel of a "class" statement is executed once > before the metaclass is called and the class object created > * all this will occur for each of your django server processes > * you can have multiple processes serving the same django application, > and ay request can be mapped to any process (this depends on the front > server and gateway so you have no control over this) > > To make a long story short: remember you are in a long running > process, so never modify (mutate or rebind) any module or class > attribute when serving a request. > > As an exemple, I once spent quite a few hours debugging a seemingly > intermittent and very very strang problem on a form. The root problem > was a younger co-worker wrote code that was mutating some of the > form's *class* attributes in the class initializer, and depending on > which process would process the form's submission, things would - or > not - get totally mixed up. > > A more common mistake is to initialize a class or module date > attribute with the result of a call to datetime.datetime.now() and > wonder why it's not updated on each and every request. -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
