5.6.7 TypeOf...Is Expressions

Note

This section describes the implementation of MS-VBAL §5.6.7 TypeOf...Is Expressions.

Syntax

Expression	AST node
TypeOf <expr> Is <type>	TypeOfIsExpressionNode

See RD-VBAL §3.0.2 Node Types. An intrinsic type written as the type is a BuiltInTypeExpressionNode, so that it can be refused where it is written.

Static semantics

What is tested is declared as a user-defined type, a class, Object or Variant, written without parentheses; anything else is VBC09310 Type mismatch (a Long), or VBC00001 Syntax error (TypeOf (o) Is Collection).

The type is the name of a class, an interface, a user-defined type or an Enum type, bare or qualified, or Object. What MS-VBA refuses there, RD-VBA refuses the same way (recorded in Excel):

The type is	Example	Error
An intrinsic type other than Object	TypeOf o Is Long, TypeOf o Is Date	VBC00001 Syntax error
No name	TypeOf o Is Nothing, TypeOf o Is Object(), TypeOf o Is String * 2	VBC00001 Syntax error
A procedural module, a library's module, or a project	TypeOf o Is Globals, TypeOf o Is Strings, TypeOf o Is VBA	the error of a declared type of that name (RD-VBAL §5.6.16.7)
Any other name: a variable's, a procedure's, or nothing's	TypeOf o Is Count, TypeOf o Is Widgit	VBC09311 User-defined type not defined

Runtime semantics

What is tested	The type	Result
Nothing	any	run-time error 91 Object variable or With block variable not set
An object	its class, or an interface its class implements	True
An object	Object	True
An object	another class, a user-defined type, an Enum type	False
A value that is no object: a Variant holding a number, a record	any	False

Error 91 for Nothing is MS-VBAL §5.6.7's, and MS-VBA's (recorded in Excel): test o Is Nothing first.

---

⏮️ RD-VBAL §5.6.6 Parenthesized Expressions | ⏭️ RD-VBAL §5.6.8 New Expressions