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TvxVariableList

TvxVariableList = class(TvxThreadList)

Example​

procedure ScriptEvent(var Value: Variant);
var WorkVar: TvxVariable;
begin
  WorkVar := Locals['BatchReference'];
  WorkVar.AsString := 'EXAMPLE';
  Value := WorkVar.AsString;
end;

Usage​

TvxVariableList provides named variables used by Globals, Locals, Settings and AzureSecrets. A variable is loaded when its code is first requested and remains available until it is removed or all variables are cleared.

Ownership and invalidation

RemoveVariable removes matching entries; FreeAllVariables removes all entries. Either operation also makes any associated dataset unavailable.

Do not retain a variable or its dataset across these operations, and never clear shared variables during ordinary record processing.

Code matching is case-insensitive. Repeated access does not refresh the source value; remove the variable first when a reload is required.

Additional Technical Info​

TvxVariableList owns a lazy case-insensitive cache of TvxVariable objects. It is the script-visible class used by Globals, Locals, Settings and inherited by AzureSecrets; each host determines the list's scope and initial-value source.

Scripts do not construct or free these lists. Globals and Settings are process singletons, AzureSecrets is process-global, and Locals belongs to the current action context.

Lazy lookup

The default Variable property locks the list and linearly searches cached Code values using AnsiCompareText. A miss creates an unowned variable, preserves the exact requested Code, calls the class's virtual initial-value hook, caches the object and unlocks.

Base lists initialise a missing value to Null. Settings performs synchronous system-database I/O and AzureSecrets can authenticate/call Key Vault. Those descendant operations run while the list lock remains held, so one slow miss blocks every lookup/invalidation on that list.

Missing and failed values are cached. Source updates or transient recovery are not observed automatically. Explicit removal/all-clear forces later lazy acquisition.

Created 2026-07-15