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| -rw-r--r-- | docs/designdefense.rst | 45 |
1 files changed, 24 insertions, 21 deletions
diff --git a/docs/designdefense.rst b/docs/designdefense.rst index 530a9c17c..98005f3f9 100644 --- a/docs/designdefense.rst +++ b/docs/designdefense.rst @@ -1405,7 +1405,9 @@ great fit for very large applications and applications that need to be arbitrarily extensible. -"Stacked Object Proxies" Are Too Clever / Thread Locals Are A Nuisance +.. _thread_local_nuisance: + +"Stacked object proxies" are too clever / thread locals are a nuisance ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Some microframeworks use the ``import`` statement to get a handle to an @@ -1448,32 +1450,33 @@ code below: for i in range(10): print(i) -By its nature, the *request* object created as the result of a WSGI server's -call into a long-lived web framework cannot be global, because the lifetime -of a single request will be much shorter than the lifetime of the process -running the framework. A request object created by a web framework actually -has more similarity to the ``i`` loop counter in our example above than it -has to any comparable importable object defined in the Python standard +By its nature, the *request* object that is created as the result of a WSGI +server's call into a long-lived web framework cannot be global, because the +lifetime of a single request will be much shorter than the lifetime of the +process running the framework. A request object created by a web framework +actually has more similarity to the ``i`` loop counter in our example above +than it has to any comparable importable object defined in the Python standard library or in normal library code. However, systems which use stacked object proxies promote locally scoped -objects such as ``request`` out to module scope, for the purpose of being +objects, such as ``request``, out to module scope, for the purpose of being able to offer users a nice spelling involving ``import``. They, for what I -consider dubious reasons, would rather present to their users the canonical -way of getting at a ``request`` as ``from framework import request`` instead -of a saner ``from myframework.threadlocals import get_request; request = -get_request()`` even though the latter is more explicit. +consider dubious reasons, would rather present to their users the canonical way +of getting at a ``request`` as ``from framework import request`` instead of a +saner ``from myframework.threadlocals import get_request; request = +get_request()``, even though the latter is more explicit. It would be *most* explicit if the microframeworks did not use thread local -variables at all. Pyramid view functions are passed a request object; many -of Pyramid's APIs require that an explicit request object be passed to them. -It is *possible* to retrieve the current Pyramid request as a threadlocal -variable but it is a "in case of emergency, break glass" type of activity. -This explicitness makes Pyramid view functions more easily unit testable, as -you don't need to rely on the framework to manufacture suitable "dummy" -request (and other similarly-scoped) objects during test setup. It also -makes them more likely to work on arbitrary systems, such as async servers -that do no monkeypatching. +variables at all. Pyramid view functions are passed a request object. Many of +Pyramid's APIs require that an explicit request object be passed to them. It is +*possible* to retrieve the current Pyramid request as a threadlocal variable, +but it is an "in case of emergency, break glass" type of activity. This +explicitness makes Pyramid view functions more easily unit testable, as you +don't need to rely on the framework to manufacture suitable "dummy" request +(and other similarly-scoped) objects during test setup. It also makes them +more likely to work on arbitrary systems, such as async servers, that do no +monkeypatching. + Explicitly WSGI +++++++++++++++ |