Omnis Classic — JACSoft Patterns

This page documents common patterns used in JACSoft Omnis Classic code.

🧠 General Style

• Procedural (not object-oriented)
• Field names used directly
• Variables prefixed (LB_, LC_, LN_, etc.)
• Boolean values are 0 / 1
• pick() uses positional logic

💾 File Update Pattern

Centralised update procedure:

Call procedure MAg_Files/1 {Do update}

Underlying behaviour:

Prepare for update
... changes ...
Update files

Cancel:

Cancel prepare for update

🔑 Primary Key Pattern

Typical pattern for new records:

Repeat
   Call procedure $createPrimaryKey
   Calculate [PK_Field] as LN_PKey
   Test for a unique index value on [PK_Field]
   Update files
Until LB_Test

📂 File Context

• Operations act on the current file
• sys(82) used to determine file name
• Record buffer is implicit

🔍 Find Pattern

Single record:

Find on FAC_Seq

Used before:

• Prepare for update
• Editing fields

📋 List Handling

• Lists use field names as columns
• Access via:

<!-- -->

FL_List.FieldName
nam(FieldName)

• Common functions:
  • totc()
  • maxc()
  • minc()

🔄 pick() Usage

Example:

Calculate PN_Value as pick(LB_Ok,ValueIfFalse,ValueIfTrue)

• 0 → first value\
• 1 → second value

🧱 Reversible Blocks

Used for controlled updates:

Begin reversible block
...
End reversible block

🧓 Final Rule

Follow existing JACSoft code patterns.

Do not modernise, refactor, or “improve” syntax unless explicitly required.