Table of Contents

5.6.16 Constrained Expressions

Note

This section describes the implementation of MS-VBAL §5.6.16 Constrained Expressions.

5.6.16.1 Constant Expressions

This section corresponds to MS-VBAL §5.6.16.1 Constant Expressions.

Note

Reserved. This section has no content yet.

5.6.16.2 Conditional Compilation Expressions

Note

This section describes the implementation of MS-VBAL §5.6.16.2 Conditional Compilation Expressions.

Precompiler constants are interpreted as Integer values. A precompiler constant value is a PrecompilerConstantValue, an additional numeric data value. See RD-VBAL §2.5.2.1.1 Numeric Values.

5.6.16.3 Boolean Expressions

This section corresponds to MS-VBAL §5.6.16.3 Boolean Expressions.

Note

Reserved. This section has no content yet.

5.6.16.4 Integer Expressions

This section corresponds to MS-VBAL §5.6.16.4 Integer Expressions.

Note

Reserved. This section has no content yet.

5.6.16.5 Variable Expressions

This section corresponds to MS-VBAL §5.6.16.5 Variable Expressions.

Note

Reserved. This section has no content yet.

5.6.16.6 Bound Variable Expressions

This section corresponds to MS-VBAL §5.6.16.6 Bound Variable Expressions.

A bound variable expression - the target of an LSet or an RSet statement, the control variable of a For or a For Each loop, the string argument of a Mid statement, an input variable of an Input # statement - "is invalid if it is classified as something other than a variable expression". A constant or a function of the library there is VBC09333 (VariableRequired), whatever its declared type; see RD-VBAL §5.4.3.8 Let Statement, which states the rule for the target of every assignment, RD-VBAL §5.4.3.5 Mid Statement and RD-VBAL §5.4.5 File Statements.

5.6.16.7 Type Expressions

This section corresponds to MS-VBAL §5.6.16.7 Type Expressions.

A type expression that is not a reserved data-type name binds under the type binding context (RD-VBAL §2.3.1.3 Name Resolution), and is invalid if what it binds is not a type: a user-defined type, an Enum type or a class is a type, and a procedural module or a project is not. A type qualified by a module binds that module's own type, whatever else has its bare name: Mod2.Helpers, beside a procedural module Helpers, is Mod2's type (RD-VBAL §2.3.1.3 Name Resolution).

What a type expression binds that is no type is an error of its own, as MS-VBA has it (recorded in Excel), wherever a type is written: the As clause of a declaration (a variable, a constant, a parameter, a result, a field of a user-defined type, a local of any procedure), the As clause of a ReDim, and the type of a TypeOf ... Is (RD-VBAL §5.6.7).

It binds Example Error
A procedural module of the project Dim g As Globals VBC09366 A module is not a valid type
A procedural module of a library Dim s As Strings, Dim s As VBA.Strings VBC09373 Automation type not supported in Visual Basic
A project or a library Dim p As VBA VBC09374 Expected user-defined type, not project
Nothing that is a type, or nothing at all Dim w As Widgit VBC09311 User-defined type not defined

New naming a procedural module is VBC09310 Type mismatch, as is New naming anything else that binds but is not a class; New with a name nothing declares is VBC09311 (RD-VBAL §5.6.8 New Expressions).

An intrinsic type written where a value is (x = Long, Debug.Print Variant) is VBC00001 Syntax error, as MS-VBA has it: a type is no value. Object is no reserved type name there, and is read as a name, as MS-VBA reads it (Debug.Print Object is Variable not defined under Option Explicit).

Note

Not implemented.

  • The declared type of a field of a user-defined type, or of a local constant, is checked only for a module or a project: a name that does not resolve there is not refused (s As Missing in a Type, or Const c As Missing = 1 in a procedure, loads) (RD-VBAL §5.0 Semantics).
  • A declared type qualified by the name of the enclosing project is VBC09311 though it names a type, since the qualifier does not resolve: Dim w As Project1.Widget.

5.6.16.8 AddressOf Expressions

This section corresponds to MS-VBAL §5.6.16.8 AddressOf Expressions.

AddressOf <procedure> is an argument, and only an argument, as the grammar of MS-VBAL has it: x = AddressOf P is a syntax error, as it is in MS-VBA. As in MS-VBA (recorded in Excel):

  • Static semantics. What it names is a Sub, a Function or a Property Get of a standard module, named bare or qualified by its module, Private ones of the module it is written in included. A variable is VBC09364 Expected Sub, Function, or Property, and a member of a class module or of an object VBC09367 Invalid use of AddressOf operator. Its declared type is implementation-defined: it is the environment's LongPtr, which a LongPtr or a Variant parameter takes - and a Long one does not, in a 64-bit environment (RD-VBAL §5.5.1.1).
  • Runtime semantics. It is the address of the procedure in the session's memory: never 0, the same every time, bare or qualified, and another for another procedure (RD-VBAL §2.3.1.2 Session Services). The address is made the first time it is asked for and lasts as long as the session; what is at it reads as zeros, and a POKE there is refused.
Note

🚧 Not implemented yet (*Ptr plan phase B): native code given the address - the callback of EnumWindows, say - has nothing it can call that runs the procedure. In MS-VBA the procedure runs inside the native call, and an error raised in it is the error of the Declare call.

⏮️ RD-VBAL §5.6.15 With Expressions | ⏭️ RD-VBAL §6.0 Standard Library

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