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Re: Reason to deprecate check_recursion() ?

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On 03/31/2014 03:24 PM, Lionel Sausin wrote:

Le 31/03/2014 14:57, Lionel Sausin a écrit :

Dear Olivier,
In v7 I just noticed that check_recursion() is deprecated in favor of
_check_recursion().
That makes it a protected method, so by convention it should only be
used inside osv.orm shouldn't it?
Not really. Quoting PEP-8, the single underscore prefix in Python is only seen as a "weak 'internal use' indicator". It separates public from non-public members, but that doesn't mean non-public members are cannot be part of the "subclass API" (aka protected). PEP-8 explicitly suggests [1] the double leading underscore (name mangled) convention for members that subclasses should not use.
In OpenERP the leading underscore convention similarly distinguishes public vs non-public API methods: underscore-prefixed methods are not available in the RPC API, and only meant for internal/subclass use. 


[1] http://legacy.python.org/dev/peps/pep-0008/#designing-for-inheritance



Would you please be kind enough to explain the reason for this and if
it's OK to call _check_recursion() in our own "Model"s?
I'm asking because now pylint is looking down on me for using a
protected method - I just want to make I'm doing it right.
It's fine to call _check_recursion in your own Models. That method is non-public because it is relatively low-level and could be a vector of SQL injection. It's been deprecated for a while, even in 6.0 IIRC.
You can configure pylint globally to exclude that warning, or use pylint comments to achieve the same. 




Uh ok, I figured out I need to override _check_recursion in my own Model
anyway...
Sorry for the noise.

      def _check_recursion(self, cr, uid, ids, context=None, parent=None):
          return super(MyOwnModel, self)._check_recursion(
              cr, uid, ids, context=context, parent=parent)
There is no need to override it unless you need to alter its behavior. The following should work along with the relevant import: 

_constraints = [
  (osv.Model._check_recursion, 'Better error message', ['parent_id'])
]

References

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