Implement mechanism for copying mixin columns without copying data

Currently there is no generic mechanism for making a "light" reference copy of mixin columns, i.e. a new object with new meta but with the same data. In the case of making a copy with copy_data=False, Table now uses literally the original object, with ensuing problems:

In [22]: t1 = QTable([[1] * u.m, ['x']])
In [23]: t1['col0'].info.description = 'quant'
In [24]: t1['col1'].info.description = 'column'

In [25]: t2 = t1.copy(copy_data=False)
In [26]: t2['col0'].info.description = 'CHANGED'
In [27]: t2['col1'].info.description = 'CHANGED'

# Original column meta is impacted!
In [28]: t1['col0'].info.description
Out[28]: 'CHANGED'

In [29]: t1['col1'].info.description
Out[29]: 'column'

This needs to be fixed, e.g. for #8077 to work properly.

Note: with 9009 then do go back to #8077 and improve the implementation to not make any copies!

@taldcroft

@taldcroft - looks like this was fixed in the meantime:

In [8]: t1 = QTable([[1] * u.m, ['x']])

In [9]: t1['col0'].info.description = 'quant'

In [10]: t1['col1'].info.description = 'column'

In [11]: t2 = t1.copy(copy_data=False)

In [12]: t2['col0'].info.description = 'CHANGED'

In [13]: t2['col1'].info.description = 'CHANGED'

In [14]: t1['col0'].info.description
Out[14]: 'quant'

In [15]: t1['col1'].info.description
Out[15]: 'column'

safe to close?

Yes, safe to close.

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Implement mechanism for copying mixin columns without copying data #9009

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Implement mechanism for copying mixin columns without copying data #9009

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taldcroft commented on Oct 22, 2019

astrofrog commented on Jun 3, 2026

taldcroft commented on Jun 3, 2026

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