Static code analysis can find hundreds of opportunities in VBA code.
Rubberduck builds its own internal representation of the code, and then proceeds to analyze it. Each individual inspection can easily be disabled, or configured to issue inspection results at different severity levels ranging from Hint to Error.
Use the Inspection Results toolwindow to review Rubberduck’s findings, search, filter, regroup results by inspection, location, type, or severity. Each inspection result comes with a detailed description of what’s being flagged and why, so you can make an enlightened decision.
Unless configured otherwise, Rubberduck automatically runs inspections after the a parser/resolver cycle completes (regardless of whether the inspection results toolwindow is displayed or not).
For the best experience, it would be recommended to first try Rubberduck with an empty project, add a new module, and write, say, a loop that counts 1 to 10 and outputs to the debug pane - then to parse that and review the inspection results; carefully review the inspection settings, and consider disabling the inspections that irreconcilably clash with your preferences: use meaningful names alone can easily produce hundreds upon hundreds of results if you’re not that much into using vowels, or if you, say, prefix all your variable names; these inspections can be re-enabled anytime you’re ready!
This tab lists all items found in the .xml documentation assets from the latest pre-release build. To modify this content, a pull request must be merged into the [next] branch.
Locates assignments to object variables for which the RHS does not have a compatible declared type.
Default severity: Warning
The VBA compiler does not check whether different object types are compatible. Instead there is a runtime error whenever the types are incompatible.
Identifies identifiers that hide/"shadow" other identifiers otherwise accessible in that scope.
Default severity: DoNotShow
This inspection will not run by default, it must be manually enabled in Code Inspections configuration settings.
Global namespace contains a number of perfectly legal identifier names that user code can use. But using these names in user code effectively "hides" the global ones. In general, avoid shadowing global-scope identifiers if possible.
Locates ThisWorkbook.Worksheets and ThisWorkbook.Sheets calls that appear to be dereferencing a worksheet that is already accessible at compile-time with a global-scope identifier.
Default severity: Suggestion
Sheet names can be changed by the user, as can a worksheet's index in ThisWorkbook.Worksheets. Worksheets that exist in ThisWorkbook at compile-time are more reliably programmatically accessed using their CodeName, which cannot be altered by the user without accessing the VBE and altering the VBA project.
This inspection will only run if the Excel library is referenced.
Locates 'For' loops where the 'Step' token is omitted.
Default severity: DoNotShow
This inspection will not run by default, it must be manually enabled in Code Inspections configuration settings.
Out of convention or preference, explicit 'Step' specifiers could be considered mandatory; this inspection can ensure the consistency of the convention.
Locates 'For' loops where the 'Step' token is specified with the default increment value (1).
Default severity: Hint
Out of convention or preference, explicit 'Step 1' specifiers could be considered redundant; this inspection can ensure the consistency of the convention.
Locates 'Stop' instructions in user code.
Default severity: Suggestion
While a great debugging tool, 'Stop' instructions should not be reachable in production code; this inspection makes it easy to locate them all.
Warns about Rubberduck annotations with more arguments than allowed.
Default severity: Warning
Most annotations only process a limited number of arguments; superfluous arguments are ignored.
Identifies assignments without Set for which both sides are objects.
Default severity: Warning
Whenever both sides of an assignment without Set are objects, there is an assignment from the default member of the RHS to the one on the LHS. Although this might be intentional, in many situations it will just mask an erroneously forgotten Set.
Warns when a variable is referenced prior to being assigned.
Default severity: Error
An uninitialized variable is being read, but since it's never assigned, the only value ever read would be the data type's default initial value. Reading a variable that was never written to in any code path (especially if Option Explicit isn't specified), is likely to be a bug.
Warns about implicit local variables that are used but never declared.
Default severity: Error
If this code compiles, then Option Explicit is omitted and compile-time validation is easily forfeited, even accidentally (e.g. typos).