pyvista.allow_new_attributes

pyvista.allow_new_attributes#

allow_new_attributes = <pyvista.core.utilities.state_manager._AllowNewAttributes object>#

Context manager to control setting new attributes on PyVista classes.

Python allows arbitrarily setting new attributes on objects at any time, but PyVista’s classes do not always allow this. By default, setting a new attribute is only allowed when the attribute’s name has a leading underscore “_”, i.e. it is a private attribute; attempting to set a new public attribute raises an AttributeError.

This context manager may be used to allow or disallow setting any new attribute, public or private, either globally or within a context.

Added in version 0.47.

Parameters:
mode‘private’ | bool

Control if setting new attributes is allowed.

  • 'private': Allow setting private attributes, but do not allow setting public attributes.

  • True: Allow setting any new attribute, either private or public.

  • False: Do not allow setting new attributes, regardless if they are private or public.

'private' is used by default, True removes all restrictions, and False is most strict.

Note

An attribute is considered private if its name has a leading underscore “_”.

See also

pyvista.set_new_attribute

Function for setting any new attribute on a PyVista object.

Notes

Allowing new attributes by default outside __init__ and/or without formally defining class properties was found to be a source of bugs for both developers and users of PyVista. It’s very easy to set the wrong attribute name (e.g. interpolate vs. interpolation) without any errors being generated, and users transitioning from older versions of PyVista would have code that sets attributes which were once valid, but have since been deprecated and removed. Attempting to set an attribute which is not already defined now raises an AttributeError to clearly signal that there is a potential problem with this line of code.

Examples

Get the default attribute mode.

>>> import pyvista as pv
>>> pv.allow_new_attributes()
'private'

Setting new private attributes on PyVista objects is allowed by default.

>>> mesh = pv.PolyData()
>>> mesh._foo = 42  # OK
>>> mesh.foo = 42  # ERROR

Do not allow setting new attributes.

>>> _ = pv.allow_new_attributes(False)
>>> mesh._foo = 42  # ERROR
>>> mesh.foo = 42  # ERROR

Note that this state is global and will persist between function calls. Set it back to its original state explicitly.

>>> _ = pv.allow_new_attributes('private')

Use it as a context manager instead. This way, the state is only temporarily modified and is automatically restored.

>>> with pv.allow_new_attributes(True):
...     mesh._foo = 42  # OK
...     mesh.foo = 42  # OK

>>> pv.allow_new_attributes()
'private'
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