PROforma Expressions: Overview
Expressions overview
Expressions are text strings that are evaluated by the Tallis Engine in order to obtain information about the current state of a process-description during its enactment. The value of an expression is dependent on the state of the process.
Conditions
Conditions are expressions that evaluate to truth-values; they occur in the several task attributes:
| State trigger | An expression that has to be true before the task can be executed (if false, the task remains dormant and waits for it to become true). | |
| Precondition | An expression that has to be true before the task can be executed (if false, the task is discarded). | |
| Cycle until | An expression defining the conditions under which a task stops cycling. | |
| Abort Condition(Plans) | An expression defining the conditions under which a plan’s state is set to discarded. | |
| Terminate Condition (Plans) |
An expression defining the conditions under which a plan’s state is set to completed. | |
| Condition (Decision arguments) |
An expression defining the conditions under which the argument applies. | |
| Recommendation Rule (Decision candidates) |
An expression defining the conditions under which a candidate is recommended. | |
Expressions can also evaluate to an integer, a real number, a text string, a set of integers, a set of real numbers, a set of text strings, or to the special value unknown.
Browse through a process-description sample:
- Cold And Flu Guide
- All three actions scheduled to run after the Diagnosis decision have preconditions; the Recommend Vaccine action has a state trigger.
- If you have installed the Tallis Toolset, you can find this sample in the World > Samples folder in the ACL Web Repository.
Run this sample file- Click here for a detailed description of this sample.
Assertions
An assertion is a text string describing values to be assigned to data items during the enactment of a process-description. Assertions occur in postconditions:
| Postcondition | An assertion that is executed when the task has been performed; often used to specify information that will be needed by subsequent tasks. |
Browse through a process-description sample:
- BMI
- Both the Metric measures enquiry and the Imperial measures enquiry have postconditions.
- If you have installed the Tallis Toolset, you can find this sample in the World > Samples folder in the ACL Web Repository.
- Run this sample file
- Click here for a detailed description of this sample.
Learn more about:
- PROforma Functions
- Frequently Used Expressions
- Frequently used expressions
- Chronic Cough
- The Scheduling decision is followed by two plans: CXR first and CXR in parallel. Depending on the decision result, one of the plans is activated and the other is discarded. The Cause decision is followed by four plans. One or more of them would be activated, depending on the decision results. The Patient information enquiry is followed by two enquiries: Initial assessment - male patient and Initial assessment - female patient. Depending on the data collected by the Patient information enquiry, one enquiry is activated and the other is discarded.
- If you have installed the Tallis Toolset, you can find this sample in the World > Samples folder in the ACL Web Repository.
- Run this sample file
- Click here for a detailed description of this sample.
- Cold And Flu Guide
- The Recommend Vaccine action has a state trigger and is only activated for patient’s over 65.
- If you have installed the Tallis Toolset, you can find this sample in the World > Samples folder in the ACL Web Repository.
- Run this sample file
- Click here for a detailed description of this sample.
- Hypertension
- The Setting BP values action has a postcondition which sets the target systolic and the target diastolic blood pressure values according to the result of the Target BP decision.
- If you have installed the Tallis Toolset, you can find this sample in the World > Samples folder in the ACL Web Repository.
- Run this sample file
- Click here for a detailed description of this sample.
- Expression Editor
Further reading: