Updated cache bahaviour of Polaris script and how attributes are updated in InstrumentSettings to fix a bug found when making subsequent calls to focus

[warunawickramasingha]

Description of work

Updated cache behaviour of Polaris script and how attributes are updated in InstrumentSettings to fix a bug found when making subsequent calls to focus method.

Purpose of work

It has been found that, if you have already run Polaris.focus then subsequent calls to focus will use the last empty run specified (or if not specified previously then the default in the mapping file), regardless of sample_empty user supplies.

Let's assume a, b, c, d are valid kwarg parameters for focus method

• In old behaviour:

1. polaris.focus(a=a1, b=b1, c=c1) //kwargs a, b, c would become attributes of the InstrumentSettings object
2. polaris.focus(b=b2, d=d1) //still attributes 'a' and 'c' passed at step 1) are attached to InstrumentSettings object and affect the behaviour

• New bahaviour:

1. polaris.focus(a=a1, b=b1, c=c1) //kwargs a, b, c would become attributes of the InstrumentSettings object
2. polaris.focus(b=b2, d=d1) //attributes 'a' and 'c' passed at step 1) are deleted from InstrumentSettings object
3. polaris.focus(a=a2, c=c2) //now attributes 'b' and 'd' are deleted from the InstrumentSettings object

Note - If any of the old kwargs found eligible to be deleted are available in the configuration file, they will rather be reinstated to their original values from the config file.

Fixes #38959.

Further detail of work

To test:

(1) Ask me for files
(2) Update paths in .yaml files
(3) Run this script

from mantid.simpleapi import *
import numpy as np
from isis_powder import polaris, SampleDetails

config_file_path = r"C:\Users\xhg73778\Documents\POLARIS\PR34144Files\polaris_config_example.yaml"
polaris = polaris.Polaris(config_file=config_file_path, user_name="test")

sample_details = SampleDetails(height=4.0, radius=0.2985, center=[0, 0, 0], shape='cylinder')
sample_details.set_material(chemical_formula='Si', packing_fraction=0.6)
sample_details.set_container(radius=0.3175, chemical_formula='V')
polaris.set_sample_details(sample=sample_details)

# focus
polaris.create_vanadium(first_cycle_run_no="98532", multiple_scattering=True, mayers_mult_scat_events=1)
polaris.focus(run_number="98533", input_mode='Summed', sample_empty="98532",
              mode="PDF", do_absorb_corrections=True, do_van_normalisation=True,
              van_normalisation_method="Absolute",
              empty_can_subtraction_method= "PaalmanPings",
              sample_empty_scale=1.0)

(4) Check the workspace history, the last call to the Minus algorithm should use a workspace derived from run 98532
(5) Call focus again without specifying sample_empty
(6) Raise the error The PaalmanPings absorption method requires 'sample_empty' to be supplied.

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[sf1919]

Looks like a genuine test failure so I won't re-run tests on this PR at the moment.

[warunawickramasingha]

Looks like a genuine test failure so I won't re-run tests on this PR at the moment.

It's strange that, the same test passes locally on Windows.

[sf1919]

It looks like it is failing on three operating systems for the same test so worth reviewing why.

[sf1919]

Looks like genuine test failures on Linux