X++ syntax
This article contains the syntax reference for X++.
X++ Keywords
The X++ keywords shown in the following table are reserved. These keywords cannot be used for any other purpose.
| Reserved word | Description | More information |
|---|---|---|
| ! | Not. | Relational Operators |
| != | Inequality operator (not equal to). | Relational Operators |
| # | Prefix on macro names. | How to: Use #define and #if to Test a Macro |
| & | Binary AND. | Arithmetic Operators |
| && | Logical AND. | Relational Operators |
| ( | Function call operator, which indicates the beginning of the function call. | |
| ) | Function call operator, which indicates the end of the function call. | |
| * | Multiply. The asterisk (*) is also used in X++ SQL. One use is to signify all fields from the tables on a select statement. Another use is as a wildcard with the like operator, to signify 0 to many characters of any kind. The like operator also uses the ? character. |
Arithmetic Operators |
| ^ | Binary XOR. | Arithmetic Operators |
| | | Binary OR. | Arithmetic Operators |
| || | Logical OR. | Relational Operators |
| ~ | Not. | Arithmetic Operators |
| + | Plus. | Arithmetic Operators |
| ++ | Increment. | Assignment Operators |
| += | Additive assignment. | Assignment Operators |
| , | Comma operator. Expressions separated by commas are evaluated left-to-right. | |
| - | Minus. | Arithmetic Operators |
| -- | Decrement operator. | Assignment Operators |
| -= | Subtractive assignment. | Assignment Operators |
| . | Class member access operator, for example, formRun.run accesses the run method of an object of the class type FormRun. |
|
| / | Divide. | Arithmetic Operators |
| </strong> | Escape in strings. Escapes extra quotation marks, and certain letters such as \t for tab. | |
| @ | Escape of keywords. For example, str @abstract; would fail to compile without the @ sign. Also affects literal strings, by negating the effect of the \ escape character, and by enabling the string to span more than one line in the source code. The new line is represented by one character of hexadecimal 0x0A, which is commonly called a line feed. No carriage return character of hexadecimal 0x0D is included, as in 0x0D0A. | |
| : | Field declaration or label specifier. The colon (:) character is also used on the switch statement. |
|
| :: | Used to call static (class) methods: ClassName::methodName. | |
| ; | Terminates statements. Used in for loops or as a separator of statements. |
|
| < | Less than. | Relational Operators |
| << | Left shift. | Arithmetic Operators |
| <= | Less than or equal. | Arithmetic Operators |
| = | Assignment operator. The argument to the left of "=" is set to the value of the argument to the right. | Assignment Operators |
| == | Returns true if both expressions are equal. | Relational Operators |
| > | Greater than. | Relational Operators |
| >= | Greater than or equal. | Relational Operators |
| >> | Right shift. | Arithmetic Operators |
| ? | Ternary operator. The question mark (?) character is also used by the like operator to signify exactly one character of any kind. The like operator also uses the character. |
Ternary Operator (?) |
| [ | Array declarator, open. Must be used with "]". | |
| ] | Array declarator, close. Must be used with "[". | |
| { | Indicates the beginning of a number of statements. The last of these statements must be followed by a "}". | |
| } | Indicates the end of a number of statements. A "{" must appear before the first of these statements. | |
| abstract | Class and method modifier. An abstract class cannot be constructed with the new keyword. An abstract method cannot be called. A table can also be modified as abstract by setting its Abstract property to Yes in the AOT, or by using the DictTable class. The Abstract property defaults to No, and it cannot be set unless the table is extended by another table. Each row in an abstract table must have a dependent row in a derived table. This means that each row in an abstract table has a value greater than 0 (zero) in its InstanceRelationType property field. There are no other effects from marking a table as abstract. Informally, programmers often use the term concrete to describe a class that is non-abstract. |
Method Modifiers Table Inheritance Overview |
| anytype | The method can return any data type. | Anytype |
| as | Needed when you assign a base class variable to a derived class variable. For example, given a Derived class that extends a Base class, the statement myDerived = myBase as Derived; avoids a compiler error by using the as keyword. This keyword also applies when you assign a base table variable to a derived table variable. |
Expression Operators: Is and As for Inheritance |
| asc | An option on the order by or group by clause in a select statement. The sorting is ascending. |
Select Statement Syntax |
| at | Specifies the position of a print window. | Print Statements |
| avg | Returns the average of the fields from the rows specified by the group by clause in a select statement. |
Select Statement Syntax |
| break | Immediate exit from code block. | Break Statements |
| breakpoint | Represents a breakpoint that is set for debugging purposes. To set a breakpoint in your code, write: breakpoint; |
|
| by | Part of a reserved term, such as group by and order by. | |
| byref | Specifies that the parameter being passed to the called method is being passed by reference (address), instead of by value. Byref is used in X++ when calling a .NET method that takes a parameter by reference (such as with the C# keywords out or ref). | How to: Use the byref Keyword for CLR Interop. |
| case | Selection within a switch statement. |
Switch Statements |
| catch | Used in exception handling. | Exception Handling with try and catch Keywords |
| changeCompany | Changes database settings to another company. | Change Company Design Pattern |
| class | Declares a class. | Classes in X++ |
| client | Method modifier. | Method Modifiers |
| container | Specifies a variable of type container. |
Containers |
| continue | Forces the next iteration of a loop. | Continue Statements |
| count | Returns the number of records from the rows specified by the group by clause in a select statement. |
Select Statement Syntax |
| crossCompany | Causes a select statement to return data for all companies that the user is authorized to read from. |
Cross-Company X++ Code Basics |
| date | Specifies a variable of type date. |
Dates |
| default | Default case within switch statements. |
Switch Statements |
| delegate | A class member that is able to store multiple references to methods in other classes, and to call all those methods when prompted to do so. A delegate can store references to various kinds of methods including the following:
|
Event Terminology and Keywords X++, C# Comparison: Event |
| delete_from | Allows you to delete multiple records from the database at the same time. | delete_from |
| desc | An option on the order by or group by clause in a select statement. The sorting is descending. |
Select Statement Syntax |
| display | Method modifier. | Method Modifiers |
| div | Integer division. | Arithmetic Operators |
| do | Beginning of a do...while loop. |
Do...while Loops |
| edit | Method modifier. | Method Modifiers |
| else | Conditional execution (if...else). |
if and if ... else Statements |
| eventHandler | Must be used each time you either add or delete a method reference from a delegate by using the += or -= operator. For example: myDelegate += eventHandler(OtherClass::myStaticMethod); | Event Terminology and Keywords X++, C# Comparison: Event |
| exists | Used with join clauses in select statements. |
Select Statement Syntax |
| extends | A class or interface declaration clause. If your class does not explicitly extend another class, your class is considered to extend the Object class (as if you had written "extends Object"). |
Creating a Subclass |
| false | Boolean literal. | Booleans |
| final | Class and method modifier. | Method Modifiers |
| firstFast | Used in select statements to speed up the fetch for the first row. |
Select Statement Syntax |
| firstOnly | Used in select statements to fetch only the first record. The firstOnly keyword does not guarantee that a maximum of one record is retrieved by an X++ SQL select statement. If the AOS can use the EntireTable cache to satisfy the data demands of the select statement, the firstOnly keyword is ignored. |
Select Statement Syntax Set-based Caching |
| firstOnly10 | Same as firstOnly, except returns 10 rows instead of one. | |
| firstOnly100 | Same as firstOnly, except returns 100 rows instead of one. | |
| firstOnly1000 | Same as firstOnly, except returns 1000 rows instead of one. | |
| flush | Clears an entire table cache. Here is the syntax for the flush statement applied to the buffer of type YourTable:```xpp
``` |
Set-based Caching |
| for | For loop iteration. | For Loops |
| forceLiterals | Used in select statements to reveal actual values that are used in where clauses to the Microsoft SQL Server database at the time of optimization. |
Select Statement Syntax |
| forceNestedLoop | Forces the SQL Server database to use a nested-loop algorithm to process a particular SQL statement containing a join. |
Select Statement Syntax |
| forcePlaceholders | Used in select statements to instruct the kernel not to reveal the actual values used in where clauses to the Microsoft SQL Server database at the time of optimization. |
Select Statement Syntax |
| forceSelectOrder | Forces the SQL Server database to access the tables in a join in the specified order. | Select Statement Syntax |
| forUpdate | Selects records exclusively for update. The operation to be performed on the records that are fetched is an update. Depending on the underlying database, the records may be locked for other users. | Select Statement Syntax |
| from | Part of a select statement. The from clause specifies the table in which the columns exists. |
Select Statement Syntax |
| group | Part of the group by clause in a select statement. |
Select Statement Syntax |
| if | Conditional execution. | if and if ... else Statements |
| implements | Implements an interface. | Interfaces Overview |
| insert_recordset | Copies data from one or more tables into one resulting destination table on a single server trip. | insert_recordset |
| int | Specifies a variable of type integer (32-bit). |
Integers |
| int64 | Specifies a variable of type integer (64-bit). |
Integers |
| interface | Interface declaration. | Interfaces Overview |
| is | Asks whether the object referenced by a class variable either inherits from the given class or is of the given class. For example, given a Derived class that extends a Base class, the expression (myDerived is Base) returns true. This keyword applies to class inheritance and table inheritance. |
Expression Operators: Is and As for Inheritance |
| join | Tables are joined on columns common to both tables. You can generate a single result set based on multiple tables through the use of joins. | Select Statement Syntax |
| like | Tests for matches by pattern, with wildcard symbols * and ?. The string on the right side of the like operator must use four backslash characters to represent one backslash. Examples follow:
|
Relational Operators |
| maxof | Returns the maximum of the fields from the rows specified by the group by clause. |
Select Statement Syntax |
| minof | Returns the minimum of the fields from the rows specified by the group by clause. |
Select Statement Syntax |
| mod | Returns the integer remainder of the left expression1 divided by the right expression2. Informally this is sometimes called the modulo operator. ((12 mod 7) == 5) is true. |
|
| new | Operator. Creates an instance of an anonymous class that is assignment-compatible with the named class/interface reference variables, or allocates memory for an array. | |
| next | Fetches the next record in a table. | |
| noFetch | Indicates that no records are to be fetched at present. | Select Statement Syntax |
| notExists | Used with join clauses in select statements. |
Select Statement Syntax |
| null | Symbolic constant. | |
| optimisticLock | Forces a statement to run with optimistic concurrency control, even if a different value is set on the table. | Select Statement Syntax |
| order | Part of the order by clause in a select statement. |
Select Statement Syntax |
| outer | outer join. | Select Statement Syntax |
| pause | Halts the execution of a job. The user is asked to state whether execution should continue. | Select Statements |
| pessimisticLock | Forces a statement to run with pessimistic concurrency control, even if a different value is set on the table. | Select Statement Syntax |
| Allows you to display output on the screen. | Print Statements | |
| private | Method access modifier. | Method Access Control |
| protected | Method access modifier. | Method Access Control |
| public | Method access modifier. | Method Access Control |
| real | Specifies a variable of type real. |
Reals |
| repeatableRead | Specifies that no other transactions can modify data that has been read by logic inside the current transaction, until after the current transaction completes. An explicit transaction completes at either ttsAbort or at the outermost ttsCommit. For a stand-alone select statement, the transaction duration is the duration of the select command. However, the database sometimes enforces the equivalent of repeatableRead in individual select statements even without this keyword appearing in your X++ code (depending on how the database decides to scan the tables). | For more information, see the documentation for the underlying relational database product. |
| retry | Used in exception handling. | Exception Handling with try and catch Keywords |
| return | Exits from a method. | Declaration of Methods |
| reverse | Records are returned in reverse order. | Select Statement Syntax |
| select | The select clause designates which columns or views are shown in the result set. |
Select Statements |
| server | Method modifier. | Method Modifiers |
| setting | Used with the update_recordset command. | update_recordset |
| static | Static methods may not refer to instance variables (only to static variables); may be invoked by using the class name rather than on an instance of the class ("MyClass.aStaticProcedure"). |
Method Modifiers |
| str | Specifies a variable of type string. |
Strings |
| sum | Returns the sum of the fields from the rows specified by the group by clause in a select statement. |
Select Statement Syntax |
| super | Calls the method that was overridden by the current method. | Table Methods |
| switch | Switch selection statement. | Switch Statements |
| tableLock | Obsolete; tableLock is no longer available. | |
| this | A reference to the current instance of the class. Used in X++ code inside a method of the class. Used to reference method members of the class, but not field members of the class.public str getFullName() { // Next statement fails to compile without 'this.'. return this.concatenateFirstAndLastNames(); } |
Loosely similar to the system variable that is named element. You use element in form control methods to reference the containing form. For more information, see Using Variables with Forms. |
| throw | Used in exception handling. | Exception Handling with try and catch Keywords |
| true | Boolean literal. | Booleans |
| try | Used in exception handling. | Exception Handling with try and catch Keywords |
| ttsAbort | Discards all changes in the current transaction. | Transaction Integrity |
| ttsBegin | Marks the beginning of a transaction. | Transaction Integrity |
| ttsCommit | Marks the end of a transaction. | Transaction Integrity |
| update_recordset | Allows the manipulation of row sets within one operation. | update_recordset |
| validTimeState | Filters rows that are retrieved from a valid time state table by an X++ SQL select statement. For example: select validTimeState(myDateEffective) * from xMyTable; ...or... select validTimeState(myDateFrom, myDateTo) * from xMyTable; |
Effects of Valid Time State Tables on Read and Write Operations |
| void | Identifies a method that does not return a value. | Declaration of Methods |
| where | Part of a select statement. The where clause specifies the conditions to be satisfied; that is, the rows that you want to include in the result. |
Select Statement Syntax |
| while | Iteration statement. Executes a statement or block repeatedly when a test condition is true. | While Loops while select Statements |
| window | Allows you to alter the size of the output window. | Print Statements |
Expressions Syntax
An expression in X++ is used in either a mathematical or logical way. Expressions are built on the data types of the language; that is, an expression returns a value of some type. This value can be used in calculations, assignments, conditional statements, and so on.
EBNF Description of Expressions in X++
| Term | Definition | |
|---|---|---|
| Expression | = | Simple-expression [RelationalOperator Simple-expression ] |
| RelationalOperator | = | = |
| Simple-expression | = | Simple-expression [ + |
| Term | = | Compfactor { Mult-operator CompFactor } |
| Mult-operator | = | * |
| CompFactor | = | [ ! ] [ - |
| Factor | = | Literal |
| Enum | = | EnumName :: Literal |
| Variable | = | Identifier [ [ Expression ] ] [ . Expression ] |
| FunctionCall | = | [ Expression (. |
| If-expression | = | Expression ? Expression : Expression |
Semantic restrictions apply on the preceding syntax. You cannot call any method using the :: operator. Similarly, you cannot use the this keyword without an active object; that is, if you are not within a method and so on.
Examples
| Example of expression | Description |
|---|---|
1 |
An integer literal. |
| NoYes::No | An enum-reference. |
A |
A variable-reference. |
| Debtor::Find("1") | A static method-call (returns a customer variable). |
| (A > 3 ? true : false) | An if-expression that returns true or false. |
| (select CustTable where CustTable.Account == "100").NameRef | A select-expression. Returns the nameref field in the customer table. This is a string. |
| A >= B | A logical expression. Returns true or false. |
| A + B | An arithmetic expression. Sums A and B. |
| A + B / C | Calculates B/C, and then adds this to A. |
| ~A + this.Value() | Sums binary not A and the result of the method-call Value on the object in scope (this). |
| Debtor::Find("1").NameRef | Returns the NameRef field of the found customer record. |
| Debtor::Find("1").Balance() | A method call to Balance in the customer table (Debtor::Find returns a customer). Returns the balance of the customer with account number 1. |
EBNF Overview
Extended Backus Naur Form (EBNF) is a metalanguage and is used in this guide to describe the language syntax. An EBNF definition consists of production rules, nonterminals, and terminals. The key terms are shown in the following table.
| Key terms | Example | Description |
|---|---|---|
| Terminals | Work_Team | A terminal is one character or a string of characters that never change. |
| Nonterminals | Employee |
A nonterminal is a description of part of a valid sentence in the language that is defined either by a production rule or a textual description. A nonterminal symbol can always be expanded to one or more terminal symbols. |
| Production rules | Employee = Developer | Tester |
Example
Work_Team = Manager Employee {, Employee} Employee = Developer | Tester This example defines a Work_Team as consisting of a Manager and one or more Employees. An Employee is defined as being a Developer, or a Tester. The symbols used in the example are described in the following table.
Special Symbols in EBNF
| Symbol | Description |
|---|---|
| (Expression) | Parentheses hold the symbols (terminals and nonterminals) together. They can be placed anywhere on the right side of a production rule. |
| Expression1 | Expression2 |
| [Expression] | Optional: The items between [ and ] are optional. All or none of the items in the brackets are included. |
| {Expression} | Repeat: The items between { and } are optional, but can be repeated as many times as necessary. |
For example, if the accessories you buy for your bicycle consist of a saddle, water-bottle holders, bells, and horns, and you could have either a bell or a horn, and zero, one, or more water bottle holders, and exactly one saddle, this could be expressed as: Bicycle_Accessories = saddle [bell | horn] {water_bottle_holders} This grammar defines the following possibilities: saddle saddle bell saddle horn saddle water_bottle_holder saddle bell water_bottle_holder saddle bell water_bottle_holder water_bottle_holder And so on.
X++ Grammar
This article shows the formal grammar of the X++ language.
How to Interpret the Formal BNF Grammar
This section describes the grammar of X++ in Backus Naur Form (BNF). A small example of BNF is described here.
AA ::= BB CC_SYM
BB ::= JJ_SYM
::= KK_SYM
AA is the name of a production rule. An AA requires a BB, followed by a CC_SYM. A BB is also a production rule. Therefore, BB is not a terminal. BB must be either a JJ_SYM or a KK_SYM. Both JJ_SYM and KK_SYM are terminals because they are not the names of any other production rules. CC_SYM is also a terminal.
In the BNF for X++ grammar, most of the terminals have _SYM as the suffix of their name.
The Formal X++ Grammar in BNF
This section contains the BNF that defines the grammar of X++.
CMPL_UNIT ::= RETTYPEID FUNC_HDR FUNC_HEAD BODY
::= RETTYPEID DATA_HDR CLASS_DECL
::= EXPR_HDR IF_EXPR SEMIOPT
::= RETTYPEID FUNC_HDR EVENT_DECL BODY
SEMIOPT ::= SEMICOLON_SYM
::=
CLASS_DECL ::= CLASS_HEADER LEFTBR_SYM DCL_EVENTMAP DCL_LIST RIGHTBR_SYM
CLASS_HEADER ::= ATTRIBUTE_DEF CLASS_MODIFIERS CLASSORINTERFACE STD_ID EXTENDS IMPLEMENTS
ATTRIBUTE_DEF ::= LEFT_BRKT_SYM ATTRIBUTE_INIT ATTRIBUTE_LIST RETTYPEID RGHT_BRKT_SYM
::=
ATTRIBUTE_INIT ::=
.
ATTRIBUTE_LIST ::= ATTRIBUTE
::= ATTRIBUTE_LIST LIST_SEP_SYM ATTRIBUTE
ATTRIBUTE ::= STD_ID
::= ATTRIBUTE_WITH_ARGS_BEGINS ATTRIBUTE_WITH_ARGS_ENDS
ATTRIBUTE_WITH_ARGS_BEGINS ::= STD_ID LEFT_PAR_SYM
ATTRIBUTE_WITH_ARGS_ENDS ::= ATTRIBUTE_ARGS RGHT_PAR_SYM
ATTRIBUTE_ARGS ::= ATTRIBUTE_CONSTANT
::= ATTRIBUTE_ARGS LIST_SEP_SYM ATTRIBUTE_CONSTANT
ATTRIBUTE_CONSTANT ::= INT_SYM
::= DBL_SYM
::= STR_SYM
::= DATE_SYM
::= DATETIME_SYM
::= STD_ID DBLCOLON_SYM STD_ID
::= TRUE_SYM
::= FALSE_SYM
::= INT64_SYM
::= ATTRIBUTE_INTRINSIC
ATTRIBUTE_INTRINSIC ::= INTRI_ID LEFT_PAR_SYM IARGS RGHT_PAR_SYM
CLASSORINTERFACE ::= CLASS_SYM
::= INTERFACE_SYM
CLASS_MODIFIERS ::= CLASS_MODS
::=
CLASS_MODS ::= CLASS_MODIFIER
::= CLASS_MODS RETTYPEID CLASS_MODIFIER
CLASS_MODIFIER ::= PUBLIC_SYM
::= FINAL_SYM
::= STATIC_SYM
::= ABSTRACT_SYM
::= PRIVATE_SYM
EXTENDS ::= EXTENDS_SYM STD_ID
::=
IMPLEMENTS ::= IMPLEMENTS_SYM IMPLEMENTLIST
::=
IMPLEMENTLIST ::= STD_ID
::= IMPLEMENTLIST LIST_SEP_SYM STD_ID
DCL_EVENTMAP ::=
EVENT_DECL ::= ATTRIBUTE_DEF EVENT_HEADER PARM_DCL_LIST
EVENT_HEADER ::= EVENT_MODIFIER VOID_TYPE_SYM STD_ID
EVENT_MODIFIER ::= EVENT_SYM
FUNC_HEAD ::= ATTRIBUTE_DEF FUNCNAME PARM_DCL_LIST
FUNCNAME ::= FUNCTYPE STD_ID
FUNCTYPE ::= FUNC_MODIFIERS DECL_TYPE
FUNC_MODIFIERS ::= FUNC_MODS
::=
FUNC_MODS ::= RETTYPEID FUNC_MODIFIER
::= FUNC_MODS RETTYPEID FUNC_MODIFIER
FUNC_MODIFIER ::= PUBLIC_SYM
::= PRIVATE_SYM
::= PROTECTED_SYM
::= FINAL_SYM
::= STATIC_SYM
::= ABSTRACT_SYM
::= DISPLAY_SYM
::= EDIT_SYM
::= SERVER_SYM
::= CLIENT_SYM
BODY ::= LEFTBR_SYM DCL_FUNC_LIST SEMIOPT SECAUTHZCHECK STMTLIST SECAUTHZEND RIGHTBR_SYM
SECAUTHZCHECK ::=
SECAUTHZEND ::=
RETTYPEID ::=
FUNCTION_DEF ::= FUNC_HEADER PARM_DCL_LIST LOCAL_BODY
FUNC_HEADER ::= DECL_TYPE STD_ID
PARM_DCL_LIST ::= RETTYPEID PARM_START PARM_LIST_OPT RGHT_PAR_SYM RETTYPEID
PARM_START ::= LEFT_PAR_SYM
PARM_LIST_OPT ::= PARM_LIST
::=
PARM_LIST ::= DCL_INIT
::= PARM_LIST LIST_SEP_SYM DCL_INIT
LOCAL_BODY ::= LEFTBR_SYM DCL_LIST SEMIOPT STMTLIST RETTYPEID RIGHTBR_SYM
DCL_LIST ::= DCL_LIST2
::=
DCL_LIST2 ::= DCL_STMT
::= DCL_LIST2 DCL_STMT
DCL_FUNC_LIST ::= DCL_FUNC_LIST2
::=
DCL_FUNC_LIST2 ::= DCL_STMT
::= FUNCTION_DEF
::= DCL_FUNC_LIST2 DCL_STMT
::= DCL_FUNC_LIST2 FUNCTION_DEF
DCL_STMT ::= DCL_INIT_LIST RETTYPEID SEMICOLON_SYM
DCL_INIT_LIST ::= DCL_INIT
::= DCL_CLIST ASG_CLAUSE
DCL_CLIST ::= DCL_INIT_LIST LIST_SEP_SYM STD_ID ARR_DCL_IDX
DCL_INIT ::= DECL ASG_CLAUSE
DECL ::= DECL_TYPE STD_ID ARR_DCL_IDX
DECL_TYPE ::= STR_TYPE_SYM STR_LEN
::= INT_TYPE_SYM
::= DBL_TYPE_SYM
::= DATE_TYPE_SYM
::= DATETIME_TYPE_SYM
::= TYPE_ID
::= QUEUE_TYPE_SYM
::= VOID_TYPE_SYM
::= ANY_TYPE_SYM
::= GUID_TYPE_SYM
::= INT64_TYPE_SYM
::= CLR_TYPE
CLR_TYPE ::= CLR_NAMESPACE TYPE_ID CLR_ARRAY_TYPE_EXT
::= CLR_NAMESPACE CLR_TYPE
CLR_NAMESPACE ::= TYPE_ID PERIOD_SYM
CLR_ARRAY_TYPE_EXT ::= CLR_ARRAY_SPEC
::=
CLR_ARRAY_SPEC ::= CLR_ARRAY_PART
::= CLR_ARRAY_SPEC CLR_ARRAY_PART
CLR_ARRAY_PART ::= CLR_ARRAY_LEFT_PART CLR_RECTANGULAR_LIST RGHT_BRKT_SYM
CLR_ARRAY_LEFT_PART ::= LEFT_BRKT_SYM
CLR_RECTANGULAR_LIST ::= CLR_COMMA_LIST
::=
CLR_COMMA_LIST ::= LIST_SEP_SYM
::= CLR_COMMA_LIST LIST_SEP_SYM
STR_LEN ::= INT_SYM
::=
ARR_DCL_IDX ::= LEFT_BRKT_SYM RANGE ARRAY_MEM RGHT_BRKT_SYM
::=
RANGE ::= IF_EXPR
::=
ARRAY_MEM ::= LIST_SEP_SYM IF_EXPR
::=
ASG_CLAUSE ::= INIT_START IF_EXPR
::=
INIT_START ::= ASG_SYM
ASG_STMT ::= LVAL_FLD ASSIGN IF_EXPR
::= LVAL_LIST ASG_SYM IF_EXPR
::= LVAL_FLD ASG_INC_DEC
::= ASG_INC_DEC LVAL_FLD
::= LVAL_FLD ASG_EVENT_HANDLER
ASSIGN ::= ASG_SYM
::= ASGINC_SYM
::= ASGDEC_SYM
ASG_INCDEC ::= ASGINC_SYM
::= ASGDEC_SYM
ASG_EVENT_HANDLER ::= ASG_INCDEC EVENTHANDLER_SYM LEFT_PAR_SYM QUALIFIER STD_ID RGHT_PAR_SYM
::= ASG_INCDEC EVENTHANDLER_SYM LEFT_PAR_SYM STD_ID DBLCOLON_SYM STD_ID RGHT_PAR_SYM
::= ASG_INCDEC EVENTHANDLER_SYM LEFT_PAR_SYM QUALIFIER EVAL_CLR_TYPE DBLCOLON_SYM STD_ID RGHT_PAR_SYM
ASG_INC_DEC ::= INC_SYM
::= DEC_SYM
LVAL_FLD ::= FIELD
LVAL_START ::= LEFT_BRKT_SYM
LVAL_LIST ::= LVAL_START LVALUES RGHT_BRKT_SYM
LVALUE ::= FIELD
LVALUES ::= LVALUE
::= LVALUES NEXTLVAL LVALUE
NEXTLVAL ::= LIST_SEP_SYM
IF_EXPR ::= COND_TRUE IF_EXPR
::= BOOL_EXPR
COND_TRUE ::= COND_TEST IF_EXPR COLON_SYM
COND_TEST ::= BOOL_EXPR QUEST_SYM
BOOL_EXPR ::= BOOL_EXPR LOGOP EXPR
::= EXPR
LOGOP ::= AND_SYM
::= OR_SYM
EXPR ::= SMPL_EXPR RELOP SMPL_EXPR
::= SMPL_EXPR AS_SYM STD_ID
::= SMPL_EXPR IS_SYM STD_ID
::= SMPL_EXPR AS_SYM EVAL_CLR_TYPE
::= SMPL_EXPR IS_SYM EVAL_CLR_TYPE
::= SMPL_EXPR
RELOP ::= LT_SYM
::= LE_SYM
::= EQ_SYM
::= NE_SYM
::= GT_SYM
::= GE_SYM
::= LIKE_SYM
SMPL_EXPR ::= SMPL_EXPR ADDOP TERM
::= TERM
ADDOP ::= PLUS_SYM
::= MINUS_SYM
::= PHYSOR_SYM
TERM ::= TERM MULOP CMPL_FACT
::= CMPL_FACT
MULOP ::= MULT_SYM
::= DIV_SYM
::= MOD_SYM
::= INTDIV_SYM
::= SHIFTL_SYM
::= SHIFTR_SYM
::= PHYSAND_SYM
::= PHYSXOR_SYM
CMPL_FACT ::= NOT_SYM SGND_FACT
::= SGND_FACT
SGND_FACT ::= SIGNOP FACTOR
::= FACTOR
SIGNOP ::= UMINUS_SYM
::= PHYSNOT_SYM
FACTOR ::= LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
::= CONSTANT
::= FIELD
::= DIRSEARCH
::= FUNCTION
::= INTRINSICS
::= EVAL
::= CONLITTERAL
::= NEW_CLR_ARRAY
NEW_CLR_ARRAY ::= NEW_SYM EVAL_CLR_TYPE NEW_CLR_ARRAY_PART LEFT_PAR_SYM RGHT_PAR_SYM
NEW_CLR_ARRAY_PART ::= CLR_SIZED_ARRAY CLR_NOSIZED_ARRAY_SPEC
CLR_SIZED_ARRAY ::= LEFT_BRKT_SYM CLR_SMPL_EXPR_COMMA_LIST RGHT_BRKT_SYM
CLR_SMPL_EXPR_COMMA_LIST ::= SMPL_EXPR
::= CLR_SMPL_EXPR_COMMA_LIST LIST_SEP_SYM SMPL_EXPR
CLR_NOSIZED_ARRAY_SPEC ::= CLR_NOSIZED_ARRAY_LIST
::=
CLR_NOSIZED_ARRAY_LIST ::= CLR_NOSIZED_ARRAY
::= CLR_NOSIZED_ARRAY_LIST CLR_NOSIZED_ARRAY
CLR_NOSIZED_ARRAY ::= LEFT_BRKT_SYM CLR_EMPTY_COMMA_LIST RGHT_BRKT_SYM
CLR_EMPTY_COMMA_LIST ::= CLR_EMPTY_RECT_COMMA_LIST
::=
CLR_EMPTY_RECT_COMMA_LIST ::= LIST_SEP_SYM
::= CLR_EMPTY_RECT_COMMA_LIST LIST_SEP_SYM
CONLITTERAL ::= LEFT_BRKT_SYM IF_EXPR EXPR_LIST RGHT_BRKT_SYM
CONSTANT ::= INT_SYM
::= DBL_SYM
::= STR_SYM
::= DATE_SYM
::= DATETIME_SYM
::= STD_ID DBLCOLON_SYM STD_ID
::= TRUE_SYM
::= FALSE_SYM
::= NULL_SYM
::= INT64_SYM
::= QUALIFIER EVAL_CLR_TYPE DBLCOLON_SYM STD_ID
::= QUALIFIER STD_ID DBLCOLON_SYM STD_ID
DIRSEARCH ::= DIRS_HEADER PERIOD_SYM STD_ID ARR_IDX
::= DIRS_HEADER PERIOD_SYM FLD_NUM ARR_IDX
DIRS_HEADER ::= LEFT_PAR_SYM SET_DIRS FIND_JOIN RGHT_PAR_SYM
SET_DIRS ::=
FIELD ::= QUALIFIER STD_ID ARR_IDX
::= QUALIFIER FLD_NUM ARR_IDX
::= STD_ID ARR_IDX
QUALIFIER ::= EVAL PERIOD_SYM
::= STD_ID PERIOD_SYM
FLD_NUM ::= LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
ARR_IDX ::= LEFT_BRKT_SYM SMPL_EXPR RGHT_BRKT_SYM
::=
EXPR_LIST ::= EXPR_LIST2
::=
EXPR_LIST2 ::= LIST_SEP_SYM IF_EXPR
::= EXPR_LIST2 LIST_SEP_SYM IF_EXPR
FUNCTION ::= FUNC_ID LEFT_PAR_SYM EVAL_FUNCTION_NAME PAR_LIST RGHT_PAR_SYM
EVAL_FUNCTION_NAME ::=
EVAL_NAME ::= EVAL_ID LEFT_PAR_SYM
::= STD_ID LEFT_PAR_SYM
::= STD_ID DBLCOLON_SYM STD_ID LEFT_PAR_SYM
::= SUPER_SYM LEFT_PAR_SYM
::= NEW_SYM STD_ID LEFT_PAR_SYM
::= NEW_SYM EVAL_CLR_TYPE LEFT_PAR_SYM
::= QUALIFIER EVAL_CLR_TYPE DBLCOLON_SYM STD_ID LEFT_PAR_SYM
::= QUALIFIER STD_ID LEFT_PAR_SYM
::= QUALIFIER STD_ID DBLCOLON_SYM STD_ID LEFT_PAR_SYM
EVAL_CLR_TYPE ::= NAMESPACE STD_ID
::= NAMESPACE EVAL_CLR_TYPE
NAMESPACE ::= STD_ID PERIOD_SYM
EVAL ::= EVAL_NAME PAR_LIST RGHT_PAR_SYM
PAR_LIST ::= PRM_LIST
::=
PRM_LIST ::= PAR_ELEM
::= PRM_LIST LIST_SEP_SYM PAR_ELEM
PAR_ELEM ::= IF_EXPR
::= BYREF_SYM FIELD
INTRINSICS ::= INTRI_ID LEFT_PAR_SYM IARGS RGHT_PAR_SYM
IARGS ::= STD_ID
::= STR_SYM
::= STD_ID LIST_SEP_SYM STD_ID
::=
STMTLIST ::= STATEMENTS
::=
STATEMENTS ::= STATEMENT
::= STATEMENTS STATEMENT
STATEMENT ::= COMPOUND_STMT
::= WHILE_STMT
::= FOR_STMT
::= DO_STMT
::= SEARCH_STMT
::= FIND_STMT
::= PRINT_STMT
::= WINDOW_STMT
::= IF_STMT
::= SWITCH_STMT
::= EXPR_STMT
::= PAUSE_STMT
::= BP_CLAUSE
::= BREAK_STMT
::= CONTINUE_STMT
::= RETURN_CLAUSE
::= MOVE_REC_STMT
::= THROW_STMT
::= TRY_STMT
::= RETRY_STMT
::= TTS_STMT
::= FLUSH_STMT
::= TBLLOCK_STMT
::= CHANGE_STMT
::= UPDATE_STMT
::= INSERT_STMT
::= UNCHECKED_STMT
COMPOUND_STMT ::= LEFTBR_SYM STMTLIST RIGHTBR_SYM
THROW_STMT ::= THROW_SYM IF_EXPR SEMICOLON_SYM
TRY_STMT ::= TRY_BLOCK CATCH_LIST
TRY_BLOCK ::= TRY_START STATEMENT
TRY_START ::= TRY_SYM
CATCH_LIST ::= CATCH_STMT
::= CATCH_LIST CATCH_STMT
CATCH_STMT ::= CATCH_EXPR PRE_CATCH STATEMENT POST_CATCH
CATCH_EXPR ::= CATCH_SYM LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
::= CATCH_SYM LEFT_PAR_SYM IF_EXPR LIST_SEP_SYM TABLEINSTANCE RGHT_PAR_SYM
::= CATCH_SYM
PRE_CATCH ::=
POST_CATCH ::=
TABLEINSTANCE ::= INSTANCENAME
INSTANCENAME ::= QUALIFIER STD_ID ARR_IDX
::= STD_ID ARR_IDX
RETRY_STMT ::= RETRY_SYM SEMICOLON_SYM
WHILE_STMT ::= WHILE_TEST STATEMENT
WHILE_TEST ::= WHILE LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
WHILE ::= WHILE_SYM
DO_STMT ::= DO_BODY DO_TEST SEMICOLON_SYM
DO_BODY ::= DO_HEADER STATEMENT
DO_HEADER ::= DO_SYM
DO_TEST ::= WHILE_SYM LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
FOR_STMT ::= FOR_HEADER STATEMENT
FOR_HEADER ::= FOR_TEST SEMICOLON_SYM FOR_ASG RGHT_PAR_SYM
FOR_TEST ::= FOR_INIT SEMICOLON_SYM IF_EXPR
FOR_INIT ::= FOR_SYM LEFT_PAR_SYM FOR_ASG
FOR_ASG ::= LVAL_FLD ASSIGN IF_EXPR
::= LVAL_FLD ASG_INC_DEC
::= ASG_INC_DEC LVAL_FLD
JOIN_LIST ::= JOIN_SPECS
::=
JOIN_SPECS ::= JOIN_SPEC
::= JOIN_SPECS JOIN_SPEC
JOIN_SPEC ::= JOIN_ORDER WHERE IF_EXPR
::= JOIN_ORDER
JOIN_ORDER ::= JOIN_USING
::= JOIN_USING ORDER_GROUP
JOIN_USING ::= JOIN_CLAUSE USING_INDEX STD_ID
::= JOIN_CLAUSE USING_INDEX HINT_SYM STD_ID
::= JOIN_CLAUSE
JOIN_CLAUSE ::= OUTER JOIN_SYM SELECTOPT TABLE
OUTER ::= OUTER_SYM
::= EXISTS_SYM
::= NOTEXISTS_SYM
::=
SEARCH_STMT ::= SEARCH_JOIN STATEMENT
SEARCH_JOIN ::= SEARCH_WHERE JOIN_LIST
SEARCH_WHERE ::= SEARCH_ORDER WHERE IF_EXPR
::= SEARCH_ORDER
WHERE ::= WHERE_SYM
SUM_ELEM ::= SUM_FUNC LEFT_PAR_SYM STD_ID RGHT_PAR_SYM
SUM_FUNC ::= SUM_SYM
::= AVG_SYM
::= CNT_SYM
::= MINOF_SYM
::= MAXOF_SYM
SEARCH_ORDER ::= SEARCH_USING
::= SEARCH_USING ORDER_GROUP
ORDER_GROUP ::= ORDERBY_CLAUSE OPT_GROUPBY
::= GROUPBY_CLAUSE OPT_ORDERBY
OPT_GROUPBY ::= GROUPBY_CLAUSE
::=
OPT_ORDERBY ::= ORDERBY_CLAUSE
::=
ORDERBY_CLAUSE ::= ORDER_SYM OPT_BY ORDER_ELEM
::= ORDERBY_CLAUSE LIST_SEP_SYM ORDER_ELEM
GROUPBY_CLAUSE ::= GROUP_SYM OPT_BY ORDER_ELEM
::= GROUPBY_CLAUSE LIST_SEP_SYM ORDER_ELEM
ORDER_ELEM ::= STD_ID INDEX DIRECTION
::= ORDER_QUALIFIER STD_ID INDEX DIRECTION
ORDER_QUALIFIER ::= STD_ID PERIOD_SYM
INDEX ::= LEFT_BRKT_SYM INT_SYM RGHT_BRKT_SYM
::=
DIRECTION ::= ASCEND_SYM
::= DESCEND_SYM
::=
OPT_BY ::= BY_SYM
::=
SEARCH_USING ::= SEARCH_CLAUSE USING_INDEX STD_ID
::= SEARCH_CLAUSE USING_INDEX HINT_SYM STD_ID
::= SEARCH_CLAUSE
USING_INDEX ::= INDEX_SYM
SEARCH_CLAUSE ::= WHILE_SYM SELECT_SYM SELECTOPT CROSSCOMPANY_CLAUSE VALIDTIMESTATE_CLAUSE TABLE
CROSSCOMPANY_CLAUSE ::= CROSSCOMPANY_SYM
::= CROSSCOMPANY_SYM COLON_SYM STD_ID
::=
VALIDTIMESTATE_CLAUSE ::= VALIDTIMESTATE_SYM LEFT_PAR_SYM STD_ID LIST_SEP_SYM STD_ID RGHT_PAR_SYM
::= VALIDTIMESTATE_SYM LEFT_PAR_SYM STD_ID RGHT_PAR_SYM
::=
SELECTOPT ::=
::= SELECTOPT REVERSE_SYM
::= SELECTOPT FIRSTFAST_SYM
::= SELECTOPT FIRSTONLY_SYM
::= SELECTOPT FIRSTONLY_SYM1
::= SELECTOPT FIRSTONLY_SYM10
::= SELECTOPT FIRSTONLY_SYM100
::= SELECTOPT FIRSTONLY_SYM1000
::= SELECTOPT FORUPDATE_SYM
::= SELECTOPT NOFETCH_SYM
::= SELECTOPT FORCE_SELECT_ORDER_SYM
::= SELECTOPT FORCE_NESTED_LOOP_SYM
::= SELECTOPT FORCE_LITERALS_SYM
::= SELECTOPT FORCE_PLACEHOLDERS_SYM
::= SELECTOPT REPEATABLEREAD_SYM
::= SELECTOPT OPTIMISTICLOCK_SYM
::= SELECTOPT PESSIMISTICLOCK_SYM
::= SELECTOPT GENERATEONLY_SYM
FIND_STMT ::= FIND_JOIN SEMICOLON_SYM
FIND_JOIN ::= FIND_WHERE JOIN_LIST
FIND_WHERE ::= FIND_ORDER WHERE IF_EXPR
::= FIND_ORDER
FIND_ORDER ::= FIND_USING
::= FIND_USING ORDER_GROUP
FIND_USING ::= FIND_TABLE USING_INDEX STD_ID
::= FIND_TABLE USING_INDEX HINT_SYM STD_ID
::= FIND_TABLE
FIND_TABLE ::= SELECT_SYM SELECTOPT CROSSCOMPANY_CLAUSE VALIDTIMESTATE_CLAUSE TABLE
::= DELETE_SYM SELECTOPT CROSSCOMPANY_CLAUSE VALIDTIMESTATE_CLAUSE TABLE
TABLE ::= FLD_LIST OPT_FROM
FLD_LIST ::= MULT_SYM
::= FIELD_LIST
FIELD_LIST ::= FIELD_SPEC
::= FIELD_LIST LIST_SEP_SYM FIELD_SPEC
FIELD_SPEC ::= STD_ID INDEX
::= SUM_ELEM
OPT_FROM ::= FROM_SYM STD_ID
::=
SETFIELDSMODE ::=
UPDATE_STMT ::= UPDATETABLE SET_SYM SETFIELDSMODE FIELDASSIGNMENTS OPT_WHERE JOIN_LIST SEMICOLON_SYM
UPDATETABLE ::= UPDATE_SYM SELECTOPT CROSSCOMPANY_CLAUSE STD_ID
OPT_WHERE ::= WHERE IF_EXPR
::=
FIELDASSIGNMENTS ::= FIELDASSIGNMENTS LIST_SEP_SYM FIELDASSIGNMENT
::= FIELDASSIGNMENT
FIELDASSIGNMENT ::= STD_ID INDEX ASG_SYM IF_EXPR
INSERT_PART ::= INSERT_SYM CROSSCOMPANY_CLAUSE INSERT_NAME LEFT_PAR_SYM INSERTFIELDLIST RGHT_PAR_SYM
INSERT_NAME ::= STD_ID
INSERT_STMT ::= INSERT_PART FIND_JOIN SEMICOLON_SYM
INSERTFIELDLIST ::= INSERTFIELD
::= INSERTFIELDLIST LIST_SEP_SYM INSERTFIELD
INSERTFIELD ::= STD_ID INDEX
PRINT_STMT ::= PRINT_CLAUSE AT_CLAUSE SEMICOLON_SYM
PRINT_CLAUSE ::= PRINT IF_EXPR EXPR_LIST
PRINT ::= PRINT_SYM
AT_CLAUSE ::= AT_SYM IF_EXPR LIST_SEP_SYM IF_EXPR
::=
WINDOW_STMT ::= WINDOW_SYM IF_EXPR LIST_SEP_SYM IF_EXPR AT_CLAUSE SEMICOLON_SYM
IF_STMT ::= ELSE_STMT
::= IF_CONDS
IF_CONDS ::= IF_COND STATEMENT
IF_COND ::= IF_SYM LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
ELSE_STMT ::= ELSE STATEMENT
ELSE ::= IF_CONDS ELSE_SYM
SWITCH_STMT ::= CASE_LIST RIGHTBR_SYM
CASE_LIST ::= SWITCH_SYM LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM LEFTBR_SYM
::= CASE_TESTS STMTLIST
CASE_TESTS ::= CASE_HEADER COLON_SYM
::= CASE_LIST DEFAULT_SYM COLON_SYM
CASE_HEADER ::= CASE IF_EXPR
::= CASEALT IF_EXPR
CASE ::= CASE_LIST CASE_SYM
CASEALT ::= CASE_HEADER LIST_SEP_SYM
EXPR_STMT ::= ASG_STMT SEMICOLON_SYM
::= FUNCTION SEMICOLON_SYM
::= INTRINSICS SEMICOLON_SYM
::= EVAL SEMICOLON_SYM
PAUSE_STMT ::= PAUSE_SYM SEMICOLON_SYM
BP_CLAUSE ::= BP_SYM SEMICOLON_SYM
BREAK_STMT ::= BREAK_SYM SEMICOLON_SYM
CONTINUE_STMT ::= CONTINUE_SYM SEMICOLON_SYM
RETURN_CLAUSE ::= RETURN_SYM SEMICOLON_SYM
::= RETURN_SYM IF_EXPR SEMICOLON_SYM
TTS_STMT ::= TTSABORT_SYM SEMICOLON_SYM
::= TTSBEGIN_SYM SEMICOLON_SYM
::= TTSEND_SYM SEMICOLON_SYM
FLUSH_STMT ::= FLUSH ID_LIST SEMICOLON_SYM
FLUSH ::= FLUSH_SYM
TBLLOCK_STMT ::= TABLELOCK ID_LIST SEMICOLON_SYM
TABLELOCK ::= TABLELOCK_SYM
ID_LIST ::= STD_ID
::= ID_LIST LIST_SEP_SYM STD_ID
MOVE_REC_STMT ::= NEXT_SYM TABLE SEMICOLON_SYM
CHANGE_STMT ::= CHANGE_HEADER STATEMENT
CHANGE_HEADER ::= CHANGE LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
CHANGE ::= CHANGECOMP_SYM
::= CHANGESITE_SYM
UNCHECKED_STMT ::= UNCHECKED_HEADER STATEMENT
UNCHECKED_HEADER ::= UNCHECKED_SYM LEFT_PAR_SYM IF_EXPR RGHT_PAR_SYM
X++ Language Syntax is Stricter in Microsoft Dynamics AX 2012
Starting in Microsoft Dynamics AX 2012, the syntax rules for X++ are stricter than in previous versions of the product. This article describes the syntax changes.
Table of X++ Syntax Changes
The following table displays a list of syntax changes that start in Microsoft Dynamics AX 2012.
| Area | Syntax rule | Before Microsoft Dynamics AX 2012 | Starting with Microsoft Dynamics AX 2012 | ||
|---|---|---|---|---|---|
| Escape | The backslash character </span> is rejected by the compiler for unrecognized escapes | The compiler used to accept "31\12\2002", but during run time the literal string was interpreted as a different value. | Now the following X++ statement is rejected by the compiler: str myDateString = "31\12\2002"; The proper syntax is "31\12\2002". | ||
| Exceptions | Retry is no longer allowed outside of a catch block | It was possible to write the retry keyword outside of a catch block. This caused the program to end when the retry was reached during runtime. | Now retry can occur only inside a catch block. For more information, see Exception Handling with try and catch Keywords. | ||
| Exceptions | Now you can throw and catch only int values |
It was possible to throw scalar expressions like strings and dates, such as throw "hello world";, and get no compile error. At runtime this was catch-able by a catch block that was not decorated with any specific value, such as catch {print("Catch worked.");}. |
Now the only expression you can put on the throw keyword is an int. Often the best thing to throw is Global::error("Explanation");. Often the best thing to catch is an element of the Exception enum. For more information, see Exception Handling with try and catch Keywords. |
||
| Inheritance | Downcasting can now be explicit.
|
It was possible to assign a base object to a derived object with the simple assignment operator, which is the equals sign (=). The compiler accepted these assignments, but during run time any misuse of an improper downcast assignment caused an error. |
Now all downcasts can be explicit. This is accomplished with the new as expression operator. Explicit downcasting with the as keyword is illustrated by the following code example, in which ThingClass extends Object: ThingClass myThing = new ThingClass(); Object myObject = myThing; myThing = myObject as ThingClass; // Explicit downcast, good. For more information, see Expression Operators: Is and As for Inheritance. |
||
| Inheritance | Override of a base method cannot be less accessible than the base method | It was possible to have a base method be decorated with protected and yet have an override of that method be private. | Now when a base method is protected, the override method must be either protected or public, and the override method cannot be private. For more information, see Method Access Control. | ||
| Inheritance | Override of a base method must have the exact same return type and parameter signature as the base method | Suppose a base class had a method that inputs a parameter of the Common table, which is the base of all tables. In a derived class it was possible to override the method to instead input MyTable. |
Now the parameter signatures of the base method and its override method must match exactly. Also, the return types must match exactly. For more information, see Overriding a Method. | ||
| Interfaces | Implementation of an interface method must match the parameter signature exactly | Suppose an interface had a method that input a parameter of an int. In a class that implements the interface, it was possible to write the method with a parameter of a str. |
Now the parameter signatures of the method must exactly match between the interface and the implementation of the method on a class. Also, the return types must match exactly. For more information, see Interfaces Overview. | ||
| Interfaces | A non-abstract base class that implements an interface cannot rely on a derived class for that implementation | When a base class implements an interface, it was possible for the class to not implement the methods of the interface if a derived class implemented the methods. The only limitation was that the new constructor method could not be called on the class. |
Now the compiler requires that every class that implements an interface must have or inherit a complete implementation of every method of the interface. For more information, see X++, C# Comparison: Object Oriented Programming. | ||
| Modifiers | The static modifier should not be applied to an interface | It was possible to write static interface IMyInterface {}, but the static modifier had no effect because it makes no sense in this context. | Sometime after Dynamics AX 2009 the X++ compiler might stop allowing the static modifier on interface declarations. For more information, see Interfaces Overview. | ||
| Modifiers | The static modifier must not be applied to the new constructor |
It was possible to apply the static modifier to the declaration of the new constructor method. This caused new MyClass(); to behave as a null operation. Instead, the statement MyClass::new(); would call the static new method, but that would not construct an object. |
Now the compiler issues an error when the static modifier is applied to the new method. For more information, see Constructors. |
||
| Modifiers | Use an explicit access modifier on each method | In the past the menu item of AOT > Classes > MyClass > New Method created the method without any access modifier. This meant that the method was implicitly public, although some X++ developers might not have been fully aware of the default. This created extra work later when a developer needed to modify the code in the method, because the developer had to research everywhere that the method might be called from. | Now the New Method menu item explicitly includes the private keyword in its automatic declaration of the new method. The developer can type in a different modifier if appropriate. For more information, see Method Modifiers. | ||
| Parameters | Parameters given in a call to a new constructor method must match the parameters on the new constructor method |
It was possible to pass in multiple parameters on call to a new constructor method even when the new method was declared to input no parameters. |
Now the call to the new method must exactly match the declared parameter signature of the new method. For more information, see Creating a Subclass. |
||
| Parameters | Parameters with default values must come after all parameters that do not have default values | It was possible to declare a method that takes in two parameters, and have only the first parameter offer a default value. There was no purpose to this. There was no way to accept the default of the first parameter because the call must specify a value for the second parameter and cannot omit the first parameter. | Now in the declaration of a method, any parameter that offers a default value must come after all the parameters that do not. For more information, see the following topics:
|
||
| Parameters | Override of a method must have the same default parameters as the overridden method | It was possible to declare a method as public void myMethod(int i=22){} and the override as public void myMethod(){}. But if the override method was called as derivedObject(333); an error occurred. |
Now the override method must list the same parameter types in the same sequence that they are declared in the overridden method. For more information, see Overriding a Method. | ||
| Preprocessor | A TODO in a comment must be the first non-whitespace in the first line of the comment | The X++ preprocessor used to detect the TODO keyword in a multi-line /* ... */ task comment even when the TODO appeared after other text after the first comment line. | Now the X++ preprocessor detects the TODO keyword only if TODO appears on the first line of the comment, and as the first non-whitespace in the comment. For more information, see TODO Comments for X++ Developer Tasks. |
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