Prove ordered comparison rules
Preserve raw mismatch while applying exact, reviewed transformations. Demonstrate an incorrect order and recover.
For supervisors
Read these instructions on any device. Watch or practise a chapter on a desktop or laptop, with a desktop or mobile application layout. Demonstrations use sample data and simulated scanners.
Prove ordered comparison rules
- Start capture in the focused box
Start capture in the focused box.
Start capture explicitly. Only this box collects keyboard input. These keystrokes are simulated; the course does not measure a physical scanner.
- Capture a prefixed value with outer spaces
Capture a prefixed value with outer spaces.
This prepared value has outer spaces, a literal prefix and a suffix. Exact comparison retains every original character.
- Inspect what arrived
Inspect what arrived.
Step 2 shows exactly what arrived, in quotes, with hidden characters shown as codes. Leaving step 1 pauses capture.
- Keep the raw comparison strict
Keep the raw comparison strict.
The expected identifier has neither spaces nor the prefix or suffix. Comparison rules may be useful, but they must not replace the raw evidence.
- Open explicit comparison rules
Open explicit comparison rules.
Rules change a copy of the received text, in order. The original scan and the exact comparison remain visible. They do not reprogram the scanner.
- Trim the outer ASCII spaces first
Trim the outer ASCII spaces first.
The first explicit rule removes outer ASCII spaces. The prefix and suffix still remain, so the result with these rules is still different.
- Add a second comparison rule
Add a second comparison rule.
Each added rule has its own position and arguments. Keep the order explicit so the transformation can be explained.
- Choose literal prefix removal
Choose literal prefix removal.
This removes only an exact prefix, not an arbitrary regular expression. A prefix that is not at the beginning is not silently found elsewhere.
- Set the exact prefix argument
Set the exact prefix argument.
Remove the literal ID colon prefix after outer spaces are trimmed. The suffix still remains and the exact difference is unchanged.
- Add the suffix rule
Add the suffix rule.
A third ordered rule handles the remaining suffix. The transformation list belongs to comparison only.
- Choose literal suffix removal
Choose literal suffix removal.
Choose suffix removal for the final exclamation mark. Literal arguments avoid broad transformations that could conceal useful differences.
- Set the exact suffix argument
Set the exact suffix argument.
All three rules now match the expected identifier. The exact comparison still records the original value as different.
- Demonstrate why rule order matters
Demonstrate why rule order matters.
Moving prefix removal before trimming means the raw leading space blocks the prefix match. The result with these rules must become different.
- Restore the checked transformation order
Restore the checked transformation order.
Move trimming back to the first position. The match with these rules returns without altering the original capture.