🚀 Mastering Dynamic ProcScript Compilation in Uniface with proccompile

Have you ever needed to validate and execute dynamic business rules at runtime in your Uniface applications? The proccompile statement is your secret weapon! 💪

This article is based on the Uniface Documentation 10.4, and I had assistance from AI in crafting this content.

🎯 What is proccompile?

The proccompile statement allows you to compile ProcScript code dynamically at runtime, either as an expression or condition. This powerful feature enables you to validate user-entered business rules before executing them, preventing runtime errors and creating more robust applications.

📝 Syntax Overview

proccompile /expression | /condition ProcScript {, ContextList}

Qualifiers

• /expression - Compiles the ProcScript as an expression 🧮
• /condition - Compiles the ProcScript as a condition ❓

Parameters

• ProcScript (String) - The ProcScript code to be compiled
• ContextList (Optional) - Nested list defining available objects like FIELDS, VARIABLES, ITEMS, etc.

🔄 Return Values and Status

After execution, proccompile returns:

• $result - Contains the compiled ProcScript module
• $status = 0 - Successful compilation ✅
• $status < 0 - Compilation error occurred ❌

When errors occur, $procerror contains detailed error information, and $abs($status) shows the position where the error occurred.

💡 Real-World Example: Dynamic Discount Calculator

Let's explore a practical scenario where users can define custom discount rules at runtime:

function total_cost
variables
 numeric vDiscount
endvariables

; Validate discount condition syntax
proccompile/condition DO_DISCOUNT, "FIELDS=AMOUNT"
if ($procerror < 0)
 message/error "Invalid discount condition: %%$procerror"
 return -1
endif

; Check if discount applies
if ($condition($result))
 ; Validate discount expression
 proccompile/expression DISCOUNT, "FIELDS=AMOUNT!;PRICE"
 if ($procerror < 0)
  message/error "Invalid discount expression: %%$procerror"
  return -1
 endif

 ; Calculate discount
 vDiscount = $expression($result)
else
 vDiscount = 0
endif

COST = AMOUNT * PRICE - vDiscount
return 0
end

How it Works 🛠️

In this example:

1. DO_DISCOUNT field might contain: AMOUNT>100
2. DISCOUNT field might contain: 0.1*AMOUNT*PRICE
3. The code validates both expressions before execution
4. If valid, it applies the business logic dynamically

🎨 Best Practices

• Always validate first - Use proccompile before executing dynamic code 🔒
• Handle errors gracefully - Check $procerror and provide meaningful messages 💬
• Define context properly - Specify available fields and variables in ContextList 📋
• Cache compiled results - Store $result for repeated use if needed ⚡

🌟 Why Use proccompile?

• Safety - Catch syntax errors before execution
• Flexibility - Enable user-configurable business rules
• Performance - Compile once, execute multiple times
• Debugging - Get precise error locations and descriptions

🎉 Conclusion

The proccompile statement transforms static Uniface applications into dynamic, user-configurable systems. By validating and compiling ProcScript at runtime, you can create more flexible and robust business applications that adapt to changing requirements without code modifications.

Start experimenting with proccompile in your next Uniface project - your users will appreciate the flexibility! 🚀