Knowledge Base

PRB: Compile-Time Error Occurs Instead of Run-Time Error

Article ID: 129930

Article Last Modified on 12/9/2003

Microsoft Visual Basic 4.0 Standard Edition
Microsoft Visual Basic 4.0 Professional Edition
Microsoft Visual Basic 4.0 Professional Edition
Microsoft Visual Basic 4.0 16-bit Enterprise Edition
Microsoft Visual Basic 4.0 32-Bit Enterprise Edition

This article was previously published under Q129930

SYMPTOMS

Setting a read-only property gives you a compile-time error instead of a run-time error. This behavior represents a new feature in Visual Basic version 4.0.

CAUSE

Visual Basic version 4.0 checks to see if read-only properties are being written to at compile time. That is why Visual Basic version 4.0 checks for this type of error when you select Make EXE File from the file menu, as opposed to just reporting the error at run time.

This also occurs when Running the program in the Design Environment (with Compile On Demand turned off). By using this new feature, the compiler prevents accidental writes to read-only properties. Having the compiler catch this type of error also stops the error from crashing a program during run time.

MORE INFORMATION

Steps to Reproduce Behavior

Start a new project in Visual Basic. Form1 is created by default.
Place a Combo Box on Form1.
Add the following code to the click event of Form1:
```
   Combo1.Style = 2
						
```
Choose Make EXE File from the File menu.
In the Make EXE dialog box, enter a name for your executable, and click OK. This results in the following error:
Function call on left-hand side of assignment must return Variant or Object

Additional query words: 4.00 vb4win vb4all

Keywords: kbprb KB129930