astropy.io.fits.column:ColumnAttribute

Extended Summary

Each ColumnAttribute may have a validator method defined on it. This validates values set on this attribute to ensure that they meet the FITS standard. Invalid values will raise a warning and will not be used in formatting the column. The validator should take two arguments--the Column it is being assigned to, and the new value for the attribute, and it must raise an AssertionError if the value is invalid.

The ColumnAttribute itself is a decorator that can be used to define the validator for each column attribute. For example

@ColumnAttribute('TTYPE')
def name(col, name):
    if not isinstance(name, str):
        raise AssertionError

The actual object returned by this decorator is the ColumnAttribute instance though, not the name function. As such name is not a method of the class it is defined in.

The setter for ColumnAttribute also updates the header of any table HDU this column is attached to in order to reflect the change. The validator should ensure that the value is valid for inclusion in a FITS header.