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Assigned

function Assigned(I: LongInt): Boolean;

Example​

procedure ScriptEvent(var Value: variant);
var
  Region: string;
begin
  Region := 'NZ';
  Value := Assigned(Region) and not Assigned('');
end;

Usage​

Assigned tests whether a supported scalar, string, array, class or interface value is nonzero, nonempty or non-nil.

Parameters

NameTypeDescription
Isupported valueScalar, string, array, object or interface value to test. Only the categories listed below are supported.

Returns

True when the value is assigned according to its runtime category; otherwise False.

Runtime categoryFalse whenTrue when
8-, 16- or 32-bit signed/unsigned integerNumeric value is zeroNumeric value is nonzero
Narrow string or PChar-like stringLength is zeroString is nonempty
Wide or Unicode stringLength is zeroString is nonempty
Dynamic arrayArray pointer is nilArray pointer is non-nil, including an allocated zero-length array
Class instanceObject reference is nilObject reference is non-nil
InterfaceInterface reference is nilInterface reference is non-nil

Errors

An unsupported value type raises an error instead of returning False. Use only the supported categories above or a type-appropriate test.

Usage notes

Use IsNullorEmpty for the documented Velox classification of Variant values. Use explicit array bounds, dataset state or object-specific properties when "assigned" is weaker than the condition the flow actually requires.

Additional Technical Info​

Assigned tests whether a value in one of the supported runtime categories is nonzero, nonempty or non-nil. Although the generated declaration appears to accept LongInt, the PascalScript compiler recognises this call specially and passes the actual argument type to the runtime operation.

The example is source-reviewed and is not executed by the documentation workflow.

The nominal LongInt parameter is an implementation placeholder, not the complete callable type contract. Do not use it to conclude that every value is converted to LongInt.

Implementation

The modified PascalScript compiler maps the identifier to an internal !ASSIGNED operation and compiles the actual argument without applying the public declaration's LongInt conversion. The runtime examines the resulting PascalScript base type and performs the category-specific test above.

This is not a call to Delphi System.Assigned. The name is compatible, but the shipped PascalScript runtime provides its own implementation and supported-type matrix.

Edge cases and quirks

  • Floating-point values, Variant, 64-bit integer types and other unlisted runtime types are not handled by the current operation. Passing one can fail the runtime call instead of returning a Boolean.
  • An allocated dynamic array with no elements has a non-nil array pointer and can be reported as assigned. Test its bounds or length when the business rule is "contains an item".
  • A non-nil class or interface reference says only that a reference exists. It does not prove that the referenced resource is open, connected or otherwise usable.
  • A whitespace-only string is assigned because it is not empty. Apply Trim first if whitespace-only text is considered absent.
  • The misleading LongInt signature is a generator/compiler surface quirk. It should not be copied into a type-conversion strategy.

Side effects

None. The operation reads the supplied value and does not acquire, release or mutate the referenced object.

Performance and concurrency

The test is constant-time for supported values and uses no shared mutable state. String checks read stored length information rather than scanning the contents.

Related entries

  • Comparison compares the available value-testing families.
  • IsNullorEmpty distinguishes Null, Empty, clear, string, numeric and conversion paths for a Variant.
  • Testing values explains common Velox value states.

External references

Created 2026-07-15