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.
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).
Warns about public class members with an underscore in their names.
Default severity: Warning
The public interface of any class module can be implemented by any other class module; if the public interface contains names with underscores, other classes cannot implement it - the code will not compile. Avoid underscores; prefer PascalCase names.
Finds instances of 'On Error Resume Next' that don't have a corresponding 'On Error GoTo 0' to restore error handling.
Default severity: Warning
'On Error Resume Next' should be constrained to a limited number of instructions, otherwise it supresses error handling for the rest of the procedure; 'On Error GoTo 0' reinstates error handling. This inspection helps treating 'Resume Next' and 'GoTo 0' as a code block (similar to 'With...End With'), essentially.
Flags 'Case' blocks that will never execute.
Default severity: Warning
Unreachable code is certainly unintended, and is probably either redundant, or a bug.
Flags uses of a number of specific string-centric but Variant-returning functions in various standard library modules.
Default severity: Hint
Several functions in the standard library take a Variant parameter and return a Variant result, but an equivalent string-returning function taking a string parameter exists and should probably be preferred.
Warns about identifiers that have names that are likely to be too short, disemvoweled, or appended with a numeric suffix.
Default severity: Suggestion
Meaningful, pronounceable, unabbreviated names read better and leave less room for interpretation. Moreover, names suffixed with a number can indicate the need to look into an array, collection, or dictionary data structure.
Identifies the use of bang notation, formally known as dictionary access expression.
Default severity: Warning
A dictionary access expression looks like a strongly typed call, but it actually is a stringly typed access to the parameterized default member of the object.
Identifies the use of bang notation, formally known as dictionary access expression, for which a recursive default member resolution is necessary.
Default severity: Warning
A dictionary access expression looks like a strongly typed call, but it actually is a stringly typed access to the parameterized default member of the object. This is especially misleading if the parameterized default member is not on the object itself and can only be reached by calling the parameterless default member first.