SimpleConstraint

class jwst.associations.lib.constraint.SimpleConstraint(*args, **kwargs)[source]

Bases: SimpleConstraintABC

A basic constraint.

Examples

Create a constraint where the attribute attr of an object matches the value my_value:

>>> c = SimpleConstraint(value="my_value")
>>> print(c)
SimpleConstraint({'name': None, 'value': 'my_value'})

To check a constraint, call check_and_set. A successful match will return a tuple of True and a reprocess list. >>> item = “my_value” >>> c.check_and_set(item) (True, [])

If it doesn’t match, False will be returned. >>> bad_item = “not_my_value” >>> c.check_and_set(bad_item) (False, [])

A SimpleConstraint can also be initialized by a dict of the relevant parameters: >>> init = {“value”: “my_value”} >>> c = SimpleConstraint(init) >>> print(c) SimpleConstraint({‘name’: None, ‘value’: ‘my_value’})

If the value to check is None, the SimpleConstraint will successfully match whatever object given. However, a new SimpleConstraint will be returned where the value is now set to whatever the attribute was of the object. >>> c = SimpleConstraint(value=None) >>> matched, reprocess = c.check_and_set(item) >>> print(c) SimpleConstraint({‘name’: None, ‘value’: ‘my_value’})

This behavior can be overridden by the force_unique parameter: >>> c = SimpleConstraint(value=None, force_unique=False) >>> matched, reprocess = c.check_and_set(item) >>> print(c) SimpleConstraint({‘name’: None, ‘value’: None})

Initialize a new SimpleConstraint.

Parameters:

initdict

Dictionary where the key:value pairs define the following parameters.

sourcesfunc(item) or None

Function taking item as argument used to retrieve a value to check against. If None, the item itself is used as the value.

force_uniquebool

If the constraint is satisfied, reset value to the value of the source.

testfunction

The test function for the constraint. Takes two arguments:

constraint

object to compare against.

Returns a boolean. Default is SimpleConstraint.eq

reprocess_on_matchbool

Reprocess the item if the constraint is satisfied.

reprocess_on_failbool

Reprocess the item if the constraint is not satisfied.

work_overListCategory.[BOTH, EXISTING, RULES]

The condition on which this constraint should operate.

reprocess_rules[rule[,..]] or None

List of rules to be applied to. If None, calling function will determine the ruleset. If empty, [], all rules will be used.

Methods Summary

`check_and_set`(item)	Check and set the constraint.
`eq`(value1, value2)	Check if constraint.value and item are equal.

Methods Documentation

check_and_set(item)[source]

Check and set the constraint.

Returns:

success, reprocessbool, [~jwst.associations.ProcessList[,…]]

Returns 2-tuple of

True if check is successful.

List of ProcessList.

eq(value1, value2)[source]

Check if constraint.value and item are equal.

Parameters:

value1any: The first value to compare.
value2any: The second value to compare.

Returns:

bool: True if the two values are deemed equal.