5.4.3.4 Erase Statement

Note

This section describes the implementation of MS-VBAL §5.4.3.4 Erase Statement.

Syntax

AST node	Instruction kind(s)	Notes
KeywordStatementNode (`Token`: `Erase`)	`Simple`	See RD-VBAL §3.4.2 Simple Statements.

Static Semantics

The declared type of each erase-element must be an array or a Variant.

An erase-element is "classified as a variable, property, function or unbound member" (MS-VBAL §5.4.3.4): a constant (Erase vbCrLf) is VBC09333 (VariableRequired).

A function named outside its own body - or a property of a module - is a call of it, and what it returns is what is erased. As in MS-VBA (recorded in Excel), one that takes an argument is VBC09339 Argument not optional, before what its type is (Erase Left, Erase Left$), and one whose declared type is not a Variant cannot return an array: VBC09307 Expected array (Erase F of a Function F() As Long, Erase Err, Erase Timer).

Runtime Semantics

Erase is ReDim's opposite: ReDim gives a resizable array its dimensions, and Erase takes them away again (RD-VBAL §5.4.3.3 ReDim Statement). What it does depends on which kind of array it was given, because a fixed-size array's bounds are part of its declaration and nothing at run time may change them.

Element	Effect
A resizable array	Set to an empty array of the same element type. The dimensions and the data are gone.
A `Variant` holding an array	The same. The variable keeps storing a `Variant`.
A fixed-size array	The dimensions stay. Every element is reset to its element type's default value.
A function, or a property of a module	Called: an array it returns is a copy of its own, and nothing else changes; anything else is error 13 (`Erase Now`).
Anything else	Runtime error 13, `Type mismatch`.

An Erase statement erases each element of its erase-list, in source order.

An erase-element that is not a simple name - a member access (obj.Items), an element (v(1)) - is an expression: the array is read from it, and a resizable array's emptied replacement is written back through it, as an assignment to it is. A fixed-size array is reset in place.

Implementation

Type or member	Role
`RDCore.Runtime.Semantics.Statements.ArrayStatementRuntimeSemantics`	Erases each element; see RD-VBAL §3.5.4 Execution.
VBResizableArrayValue, VBFixedSizeArrayValue	The two kinds of array the statement tells apart (RDCore.SDK).