5.3.1.6 Subroutine and Function Declarations

Note

This section describes the implementation of MS-VBAL §5.3.1.6 Subroutine and Function Declarations.

Static Semantics

VBVoidType is the data type returned by Sub, Property Let and Property Set procedures; see RD-VBAL §2.4.2 Non-intrinsic Types.

A Sub's own symbol already carries VBVoidType as its type. See RD-VBAL §5.6.10 Simple Name Expressions.

Function Result Variable

Function and Property Get return values (the function result variable) follow MS-VBAL §5.3.1 Procedure Declarations.

• Each invocation of a Function or Property Get gets a fresh function result variable.
• The function result variable is modeled as ICallStackFrame.ReturnValue, a single per-activation slot.
• ICallStackFrame.ReturnValue is read-only on the SDK interface, like ICallStackFrame.Pc; it is mutable on the runtime's CallStackFrame.
• ReturnValue is seeded to the default value of the procedure's declared return type before the procedure body runs.

Inside the procedure's own body, a bare reference to the procedure's own name is the function result variable:

Use of the procedure's own name, from within its own body	Effect	Described in
A bare reference	Reads the ReturnValue slot instead of the general symbol table.	RD-VBAL §5.6.10 Simple Name Expressions
A Let-assignment to a bare reference	Assigns the ReturnValue slot instead of the general symbol table.	RD-VBAL §5.4.3.8 Let Statement
A Set-assignment to a bare reference	Set-coerces the object to the declared result type, and assigns the ReturnValue slot: the result of a Variant function that is Set to an object holds the object.	RD-VBAL §5.4.3.9 Set Statement

A function that returns an object and never sets its result returns Nothing, which is the default value of an object type. The object a function returns is not released with the activation's locals, whether the result is declared as an object type or as a Variant that holds the object.

Invocation Result

Procedure	Result of a successful invocation
Function, Property Get	The value of its own function result variable.
Sub	VBVoidValue

RuntimeProcedureInvoker reads frame.ReturnValue back once ExitProcedure is reached, and reports it as the call's result. See RD-VBAL §5.3.1.11 Procedure Invocation Argument Processing.

A Function or Property Get that declares no parameters is not given the arguments written after it in parentheses: it is called without them, and they index what it returns. Items(1) of a function that returns a Collection is Items().Item(1), as h.Items(1) is h.Items.Item(1) for a property. The empty list of F() is not an argument.

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⏮️ RD-VBAL §5.3.1.5 Parameter Lists | ⏭️ RD-VBAL §5.3.1.7 Property Declarations