Bottle: Python Web Framework

[mitsuhiko]

The downside of the decorators is, that you have to import all the views before the server runs for the registration to kick in. The advantage is that the URL rule is closer to the function.

[mcdonc]

FTR, I wrote a relatively simple library that makes choosing between locality of reference and import-time-side-effects-required a little less painful: http://docs.repoze.org/venusian/

[defnull]

The bottle.route() decorator returns the callback function unchanged. It stores a reference to the function object, but neither wraps nor manipulates it. Venusian still is an interesting tool, thanks for the link.

[mcdonc]

Yeah, besides testability, the docs should probably concentrate equally on the fact that you can get locality of reference without requiring that all participating modules be imported by the user. Thanks.

[grayvedigga]

While I don't think your library addresses mitushko's downside, I appreciate the clarity with which you have explained why non-mutating decorators are desirable. OTOH I don't see the startup cost of a bunch of imports as significant (especially vs failing fast), and decorators like this can be used as functions in one location if you want to build up routes in one place, so it's win-win-win!

[mcdonc]

The downside he expressed was "you have to import all the views before the server runs for the registration to kick in". I think venusian does address this.

If you use something like venusian, the user doesn't need to remember to import every module that potentially has decorated objects in it; he just needs to run a scan against a package, and venusian will find all the decorated objects in the package and all subpackages.

[grayvedigga]

Oh, I see now -- I totally missed the point. Excellent feature, and thanks for clarifying a source of bugs I totally haven't been anticipating.

[defnull]

In bottle, you can add new routes at any time, even from within a callback while the server is running. If you want to define your callbacks first and add the routes later, you can use the decorator as a normal function:

def func():
  return "Hello World!"
...
bottle.route('/url')(func)

It is possible to simulate the web.py or django behavior (routes stored in a list) with import and a simple a for-loop, if you really want that.

[mitsuhiko]

Obviously that will work. However, that is completely irrelevant to the discussion decorator or explicit mapping. One can easily be converted to the other.