Rules Catalog (108 Rules)

Comprehensive reference for all 108 Clean ABAP, security, performance, and architecture rules in Skylint.

Skylint at a Glance

• 108 Native ATC Rules: 100% ABAP Cloud (Contract C1) & Steampunk Ready.
• 46 Automated QuickFixes: Instant one-click refactoring with Ctrl + 1 in Eclipse ADT.
• Zero Legacy Overhead: Built exclusively on IF_CI_ATC_CHECK (no obsolete Code Inspector / SCI dependency).

Clean ABAP & Modern Syntax (41)

Modern language features, expression-oriented coding, and idiomatic Clean ABAP practices.

Rule ID	ABAP Class	Description	Pseudo-Comment	QuickFix	Remote Enabled
prefer-reduce	ZCL_SKYLINT_PREF_REDUCE	Prefer REDUCE #( ) expression over simple aggregation LOOP	#EC PREF_REDUCE	⚡ Ready	✅ Yes
prefer-tab-expr	ZCL_SKYLINT_PREF_TAB_EXPR	Prefer table expression itab[ ... ] over READ TABLE	#EC PREF_TAB_EXPR	⚡ Ready	✅ Yes
prefer-cond	ZCL_SKYLINT_PREF_COND	Prefer COND #( ) expression over IF/ELSEIF/ELSE statement	#EC PREF_COND	⚡ Ready	✅ Yes
prefer-switch	ZCL_SKYLINT_PREF_SWITCH	Prefer SWITCH #( ) expression over CASE statement	#EC PREF_SWITCH	⚡ Ready	✅ Yes
prefer-lines	ZCL_SKYLINT_PREF_LINES	Prefer lines( ) over DESCRIBE TABLE ... LINES	#EC LINES	⚡ Ready	✅ Yes
prefer-is-not	ZCL_SKYLINT_PREF_IS_NOT	Prefer IS NOT over NOT ... IS	#EC IS_NOT	⚡ Ready	✅ Yes
prefer-string-template	ZCL_SKYLINT_PREF_STR_TMPL	Prefer string templates over CONCATENATE	#EC STR_TMPL	⚡ Ready	✅ Yes
prefer-line-exists	ZCL_SKYLINT_PREF_LINE_EXISTS	Prefer line_exists( ) over READ TABLE with NO FIELDS	#EC LINE_EXISTS	—	✅ Yes
prefer-return	ZCL_SKYLINT_PREF_RETURN	Prefer RETURN over EXIT outside loop constructs	#EC RETURN	⚡ Ready	✅ Yes
prefer-merged-ifs	ZCL_SKYLINT_PREF_MERGE_IFS	Merge consecutive nested IF blocks using boolean AND	#EC MERGE_IFS	—	✅ Yes
prefer-symbol-operators	ZCL_SKYLINT_PREF_SYMBOL_OP	Prefer symbolic operators over textual EQ, NE, LT, GT	#EC SYMBOL_OP	⚡ Ready	✅ Yes
prefer-new-operator	ZCL_SKYLINT_PREF_NEW_OP	Prefer NEW operator over CREATE OBJECT and RAISE EXCEPTION	#EC NEW_OP	⚡ Ready	✅ Yes
prefer-xsdbool	ZCL_SKYLINT_PREF_XSDBOOL	Prefer xsdbool( ) expression over manual IF-ELSE assignment	#EC XSDBOOL	⚡ Ready	✅ Yes
prefer-fully-typed	ZCL_SKYLINT_PREF_FULL_TYPED	Enforce fully typed constant declarations	#EC FULL_TYPED	—	✅ Yes
prefer-corresponding	ZCL_SKYLINT_PREF_CORRESP	Prefer CORRESPONDING Expression over MOVE-CORRESPONDING	#EC CORRESP	⚡ Ready	✅ Yes
prefer-returning	ZCL_SKYLINT_PREF_RETURNING	Prefer RETURNING over single EXPORTING	#EC RETURNING	—	✅ Yes
prefer-class-exceptions	ZCL_SKYLINT_PREF_CLASS_EXC	Prefer Class-Based Exceptions over Classic EXCEPTIONS	#EC CLASS_EXC	—	✅ Yes
prefer-final-class	ZCL_SKYLINT_PREF_FINAL_CLS	Prefer FINAL classes and methods by default	#EC FINAL_CLS	⚡ Ready	✅ Yes
prefer-insert-into	ZCL_SKYLINT_PREF_INSERT	Prefer INSERT ... INTO TABLE over APPEND for table safety	#EC INSERT_INTO	⚡ Ready	✅ Yes
prefer-predicate-names	ZCL_SKYLINT_PREF_PRED_NAME	Enforce predicate naming (IS_, HAS_) on boolean methods	#EC PRED_NAME	—	✅ Yes
prefer-string-functions	ZCL_SKYLINT_PREF_STR_FUNC	Detect obsolete string statements; prefer built-in functions	#EC STR_FUNC	⚡ Ready	✅ Yes
prefer-calc-assign-op	ZCL_SKYLINT_PREF_CALC_OP	Prefer calculation assignment operators (+=, -=, *=, /=)	#EC CALC_ASSIGN	⚡ Ready	✅ Yes
prefer-early-return	ZCL_SKYLINT_PREF_EARLY_RET	Prefer early return or continue over nested IF blocks	#EC EARLY_RETURN	—	✅ Yes
prefer-decl-order	ZCL_SKYLINT_PREF_DECL_ORDER	Enforce declaration order (TYPES, CONSTANTS, DATA, FS)	#EC DECL_ORDER	—	✅ Yes
prefer-case	ZCL_SKYLINT_PREF_CASE	Use CASE instead of IF when checking multiple values	#EC PREF_CASE	—	✅ Yes
max-one-statement	ZCL_SKYLINT_MAX_ONE_STMT	Max One Statement Per Line	#EC ONE_STMT	—	✅ Yes
prefer-inline	ZCL_SKYLINT_PREF_INLINE	Prefer Inline Declarations	#EC PREFER_INLINE	—	✅ Yes
prefer-final-data	ZCL_SKYLINT_PREF_FINAL_DATA	Declare inline variables as FINAL when never written again	#EC PREF_FINAL	⚡ Ready	✅ Yes
prefer-message-class	ZCL_SKYLINT_PREF_MSG_CLS	Use a message class instead of inline message text	#EC MSG_CLASS	—	❌ No
prefer-inline-cast	ZCL_SKYLINT_PREF_INL_CAST	Inline a CAST helper that is only read once	#EC INLINE_CAST	⚡ Ready	✅ Yes
prefer-public-constructor	ZCL_SKYLINT_PREF_PUB_CTOR	Declare Constructor in PUBLIC SECTION	#EC PUB_CTOR	—	✅ Yes
prefer-definitions-top	ZCL_SKYLINT_PREF_DEF_TOP	Place definitions at beginning of routine	#EC DEF_TOP	—	✅ Yes
max-one-method-parameter-per-line	ZCL_SKYLINT_MAX_PARAM_LINE	Max one method parameter definition per line	#EC MAX_PARAM_LINE	—	✅ Yes
prefer-is-initial	ZCL_SKYLINT_PREF_IS_INITIAL	Prefer IS [NOT] INITIAL over lines( ) or empty literals	#EC PREF_INIT	⚡ Ready	✅ Yes
prefer-cast	ZCL_SKYLINT_PREF_CAST	Prefer modern CAST #( ) expression over ?=	#EC PREF_CAST	⚡ Ready	✅ Yes
prefer-naming	ZCL_SKYLINT_PREF_NAMING	Standard Naming Conventions	#EC NAMING	—	✅ Yes
bad-indent	ZCL_SKYLINT_NO_BAD_INDENT	Bad Statement Indentation	#EC BAD_INDENT	⚡ Ready	✅ Yes
prefer-join-type	ZCL_SKYLINT_PREF_JOIN_TYPE	Prefer an explicit JOIN type such as INNER JOIN	#EC JOIN_TYPE	⚡ Ready	✅ Yes
prefer-standard-table	ZCL_SKYLINT_PREF_STD_TABLE	Prefer explicit TYPE STANDARD TABLE OF over TYPE TABLE OF	#EC PREF_STD_TABLE	⚡ Ready	✅ Yes
prefer-is-supplied	ZCL_SKYLINT_PREF_IS_SUPPLIED	Prefer IS SUPPLIED over the obsolete IS REQUESTED	#EC PREF_IS_SUPPLIED	⚡ Ready	✅ Yes
prefer-sy	ZCL_SKYLINT_PREF_SY	Prefer the short system field alias SY over SYST	#EC PREF_SY	⚡ Ready	✅ Yes

Anti-Patterns & Bad Practices (39)

Discouraged language constructs, legacy statements, and redundant syntax.

Rule ID	ABAP Class	Description	Pseudo-Comment	QuickFix	Remote Enabled
no-call-method	ZCL_SKYLINT_NO_CALL_METHOD	Avoid static CALL METHOD statements	#EC CALL_METH	⚡ Ready	✅ Yes
no-default-key	ZCL_SKYLINT_NO_DEFAULT_KEY	Avoid WITH DEFAULT KEY; prefer EMPTY KEY or explicit keys	#EC DEFAULT_KEY	⚡ Ready	✅ Yes
no-me-reference	ZCL_SKYLINT_NO_ME_REFERENCE	Avoid self-reference ME->	#EC ME	—	✅ Yes
no-redundant-method-call	ZCL_SKYLINT_NO_REDUNDANT_CALL	Omit redundant EXPORTING and RECEIVING in method calls	#EC EXPORTING	⚡ Ready	❌ No
no-chained-statements	ZCL_SKYLINT_NO_CHAINED_STMT	Avoid chained declarations and chained assignments	#EC CHAIN_DECL	⚡ Ready	✅ Yes
no-boolean-comparison	ZCL_SKYLINT_NO_BOOL_COMPARE	Avoid comparing boolean method calls to boolean literals	#EC BOOL_COMPARE	⚡ Ready	✅ Yes
no-check-statement	ZCL_SKYLINT_NO_CHECK_STMT	Avoid CHECK statements; prefer IF with RETURN or CONTINUE	#EC CHECK_STMT	⚡ Ready	✅ Yes
no-empty-block	ZCL_SKYLINT_NO_EMPTY_BLOCK	Avoid empty control blocks (IF, CASE, LOOP, TRY, etc.)	#EC EMPTY_BLOCK	—	✅ Yes
no-duplicate-conditions	ZCL_SKYLINT_NO_DUP_COND	Avoid duplicate branch conditions in IF and CASE	#EC DUP_COND	—	✅ Yes
no-unreachable-code	ZCL_SKYLINT_NO_UNREACHABLE	Detect unreachable code after jump or exit statements	#EC UNREACHABLE	⚡ Ready	✅ Yes
no-single-when	ZCL_SKYLINT_NO_SINGLE_WHEN	Avoid CASE statements with only one WHEN branch	#EC SINGLE_WHEN	—	✅ Yes
no-yoda-conditions	ZCL_SKYLINT_NO_YODA_COND	Avoid Yoda conditions in comparison expressions	#EC YODA_COND	⚡ Ready	✅ Yes
no-static-via-instance	ZCL_SKYLINT_NO_STATIC_ARROW	Avoid calling static methods via instance arrow (->)	#EC STATIC_ARROW	⚡ Ready	❌ No
no-public-attributes	ZCL_SKYLINT_NO_PUBLIC_ATTR	Avoid mutable public attributes in classes	#EC PUBLIC_ATTR	—	✅ Yes
no-obsolete-statements	ZCL_SKYLINT_NO_OBSOLETE	Avoid obsolete statements (MOVE, REFRESH, FORM, etc.)	#EC OBSOLETE	⚡ Ready	✅ Yes
no-list-processing	ZCL_SKYLINT_NO_LIST_PROC	Prohibit classic list processing statements	#EC LIST_PROC	—	✅ Yes
no-scope-leak	ZCL_SKYLINT_NO_SCOPE_LEAK	Avoid variable usage outside its declaring control block	#EC SCOPE_LEAK	—	✅ Yes
no-self-assignment	ZCL_SKYLINT_NO_SELF_ASSIGN	Detect Identical Self Assignments	#EC SELF_ASSIGN	⚡ Ready	✅ Yes
no-magic-numbers	ZCL_SKYLINT_NO_MAGIC_NUMBERS	Avoid magic numbers in code; use named constants	#EC MAGIC_NUMBERS	—	✅ Yes
no-like-objects	ZCL_SKYLINT_NO_LIKE_OBJECTS	Avoid LIKE referencing data objects; use explicit TYPE	#EC LIKE_OBJECTS	—	✅ Yes
no-static-classes	ZCL_SKYLINT_NO_STATIC_CLS	Avoid static-only classes; use instantiable classes	#EC STATIC_CLS	—	✅ Yes
no-interface-data	ZCL_SKYLINT_NO_INTF_DATA	Avoid mutable DATA in interfaces; allow only CONSTANTS	#EC INTF_DATA	—	✅ Yes
no-message-raising	ZCL_SKYLINT_NO_MSG_RAISING	Avoid MESSAGE ... RAISING; use class-based exceptions	#EC MSG_RAISING	—	✅ Yes
no-nested-try	ZCL_SKYLINT_NO_NESTED_TRY	Avoid nested TRY blocks; extract to helper methods	#EC NESTED_TRY	—	✅ Yes
no-unused-variables	ZCL_SKYLINT_NO_UNUSED_VARS	Detect unused local variables and field symbols	#EC NEEDED	—	✅ Yes
no-param-escape	ZCL_SKYLINT_NO_PARAM_ESCAPE	Avoid unnecessary parameter escape (!param)	#EC PARAM_ESCAPE	⚡ Ready	✅ Yes
no-inline-length	ZCL_SKYLINT_NO_INLINE_LEN	Avoid inline length specification in declarations	#EC PAREN_LEN	⚡ Ready	✅ Yes
no-dash-in-names	ZCL_SKYLINT_NO_DASH_IN_NAMES	No Dashes in Variable and Form Names	#EC NO_DASH	—	✅ Yes
no-friends	ZCL_SKYLINT_NO_FRIENDS	Avoid FRIENDS in class definitions	#EC FRIENDS	—	✅ Yes
no-exception-overlap	ZCL_SKYLINT_NO_EXC_OVERLAP	Classic EXCEPTIONS must not overlap	#EC EXC_OVERLAP	—	✅ Yes
no-many-parentheses	ZCL_SKYLINT_NO_MANY_PARENS	Remove redundant parentheses	#EC MANY_PARENS	⚡ Ready	✅ Yes
no-unnecessary-return	ZCL_SKYLINT_NO_UNNEC_RETURN	Omit unnecessary RETURN at end of routine	#EC NO_UNNEC_RETURN	⚡ Ready	✅ Yes
mix-returning	ZCL_SKYLINT_NO_MIX_RETURNING	Do not mix RETURNING with EXPORTING or CHANGING	#EC NO_MIX_RETURNING	—	✅ Yes
method-overwrites-builtin	ZCL_SKYLINT_NO_OVERW_BUILTIN	Method name overwrites built-in SAP function	#EC NO_OVERW_BUILTIN	—	✅ Yes
no-ignored-return-value	ZCL_SKYLINT_NO_IGNORED_RETURN	Disallow ignoring the return value of functional methods	#EC NO_IGNORED_RET	—	❌ No
no-redundant-clear	ZCL_SKYLINT_NO_REDUNDANT_CLEAR	Do not CLEAR or FREE variables redundantly	#EC REDUNDANT_CLEAR	⚡ Ready	✅ Yes
expand-macros	ZCL_SKYLINT_PREF_EXPAND_MACRO	Expand Macro Calls	#EC EXPAND_MACROS	⚡ Ready	✅ Yes
no-dead-code	ZCL_SKYLINT_NO_DEAD_CODE	Detect Dead Code with Constant Condition	#EC NO_DEAD_CODE	⚡ Ready	✅ Yes
keyword-name	ZCL_SKYLINT_NO_KEYWORD_NAME	Avoid Using ABAP Keywords as Identifier Names	#EC KEYWORD_NAME	—	✅ Yes

Performance & Database (7)

Database query efficiency, buffer protection, and internal table operation guidelines.

Rule ID	ABAP Class	Description	Pseudo-Comment	QuickFix	Remote Enabled
no-db-in-loop	ZCL_SKYLINT_NO_DB_IN_LOOP	Avoid database access inside loop iterations	#EC DB_IN_LOOP	—	✅ Yes
no-empty-fae	ZCL_SKYLINT_NO_EMPTY_FAE	Unsecure FOR ALL ENTRIES (Missing empty itab check)	#EC EMPTY_FAE	⚡ Ready	✅ Yes
no-select-star	ZCL_SKYLINT_NO_SELECT_STAR	Select performance (Avoid SELECT * and SELECT ... ENDSELECT)	#EC SELECT_STAR	—	✅ Yes
prefer-order-by	ZCL_SKYLINT_PREF_ORDER_BY	SELECT UP TO 1 ROWS requires ORDER BY	#EC ORDER_BY	—	✅ Yes
prefer-transporting	ZCL_SKYLINT_PREF_TRANSPORT	Avoid MODIFY itab in LOOP without TRANSPORTING clause	#EC TRANSPORTING	—	✅ Yes
prefer-pass-by-reference	ZCL_SKYLINT_PREF_PASS_BY_REF	Slow Parameter Passing	#EC SLOW_PARAM	—	✅ Yes
no-modify-loop-table	ZCL_SKYLINT_NO_MOD_LOOP_TAB	Avoid mutating or sorting tables inside loops	#EC LOOP_MODIFY	—	✅ Yes

Security & Robustness (12)

Authorizations, dynamic execution sanitation, error handling, and runtime safety.

Rule ID	ABAP Class	Description	Pseudo-Comment	QuickFix	Remote Enabled
no-sy-modify	ZCL_SKYLINT_NO_SY_MODIFY	Avoid sy-* System Variable Modification	#EC SY_MODIFY	—	✅ Yes
no-dangerous-statements	ZCL_SKYLINT_NO_DANGEROUS_STMT	Dangerous Statements (abaplint dangerous_statement)	#EC DANGEROUS_STMT	—	✅ Yes
prefer-auth-check	ZCL_SKYLINT_PREF_AUTH_CHECK	Call Transaction Authority Check	#EC AUTH_CHECK	⚡ Ready	✅ Yes
no-catch-cx-root	ZCL_SKYLINT_NO_CATCH_ROOT	Catch specific exceptions instead of generic cx_root	#EC CATCH_ROOT	—	✅ Yes
no-raise-cx-sy	ZCL_SKYLINT_NO_RAISE_CX_SY	Avoid raising SAP internal system exceptions (cx_sy_*)	#EC RAISE_CX_SY	—	✅ Yes
prefer-subrc-check	ZCL_SKYLINT_PREF_CHECK_SUBRC	Check sy-subrc after DB, table and string operations	#EC CHECK_SUBRC	—	✅ Yes
no-client-specified	ZCL_SKYLINT_NO_CLIENT_SPEC	Avoid USING CLIENT or CLIENT SPECIFIED in ABAP SQL	#EC CLIENT_SPEC	⚡ Ready	✅ Yes
no-commit-work	ZCL_SKYLINT_NO_COMMIT_WORK	Avoid COMMIT and ROLLBACK in application logic	#EC COMMIT_WORK	—	❌ No
no-rfc-error-handling	ZCL_SKYLINT_NO_RFC_ERR	RFC calls must handle system failures	#EC RFC_ERR	—	✅ Yes
no-modify-standard-tables	ZCL_SKYLINT_NO_MOD_STD_TABLE	Modify Only Own Database Tables	#EC OWN_TABLES	—	✅ Yes
no-dynamic-stuff	ZCL_SKYLINT_NO_DYNAMIC_STMT	No Dynamic Constructs (CALL, ASSIGN, CREATE, etc.)	#EC NO_DYNAMIC	—	✅ Yes
no-hardcoded-env-checks	ZCL_SKYLINT_NO_HARDCODED_ENV	Avoid reading environment system fields (sy-sysid, etc.)	#EC HARDCODED_ENV	—	✅ Yes

Metrics & Complexity Limits (8)

Quantitative boundaries for method size, nesting depth, parameter counts, and cyclomatic complexity.

Rule ID	ABAP Class	Description	Pseudo-Comment	QuickFix	Remote Enabled
max-params	ZCL_SKYLINT_MAX_PARAMS	Method signature cleanliness (excessive parameter count)	#EC MAX_PARAMS	—	✅ Yes
max-method-length	ZCL_SKYLINT_MAX_METHOD_LEN	Method Length Limit (excessive statement count)	#EC METHOD_LEN	—	✅ Yes
max-nesting-depth	ZCL_SKYLINT_MAX_NESTING	Nesting Depth Limit (excessive control block nesting)	#EC NESTING	—	✅ Yes
max-cyclomatic-complexity	ZCL_SKYLINT_MAX_CYCLO_COMP	Cyclomatic Complexity Threshold	#EC CYCLO_COMP	—	✅ Yes
max-constructor-statements	ZCL_SKYLINT_MAX_CTOR_STMTS	Keep constructors clean; avoid heavy logic and DB	#EC CLEAN_CTOR	—	✅ Yes
max-inheritance-depth	ZCL_SKYLINT_MAX_INHERIT	Avoid deep class inheritance hierarchies	#EC INHERIT_DEPTH	—	❌ No
max-attributes	ZCL_SKYLINT_MAX_ATTRIBUTES	Limit class member attributes to prevent God Classes	#EC ATTRIBUTES	—	✅ Yes
max-line-length	ZCL_SKYLINT_MAX_LINE_LEN	Maximum Line Length	#EC LINE_LEN	—	✅ Yes