How to use X++ macro in Dynamics 365 F&O (D365 FSCM)?

Macros in X++ are precompiler directives that let you define reusable symbols, values, or code fragments before compilation. They are powerful but considered legacy, so Microsoft recommends using language constructs instead.

🔑 Key Points About X++ Macros

What Are Macros?

• Macros are processed before compilation: The compiler never sees the directive itself, only the expanded characters.

• Legacy feature: They may be deprecated in future releases. Prefer constants or constructs like SysDa for queries.

Defining Macros

• Syntax:

  #define.MyMacro(Value)   // macro with value

  #define.AnotherMacro()   // macro without value

• Case-insensitive: Macro names and directives are not case-sensitive, but best practice is to start names with uppercase.

• Conditional checks:

  #if.MyMacro
     // Code included if defined
  #endif
  #ifnot.MyMacro
     // Code included if not defined
  #endif

Removing Macros

• #undef removes a macro definition:

  #undef.MyMacro
  

Using Macro Values

• Macros can hold character sequences (no data type).

• Example:

  #define.Offset(42)
  print #Offset;   // Outputs 42

Testing Macro Values

• You can test if a macro’s value equals a specific string.

• Best practice: always define a value or never define one—avoid mixing.

Increment/Decrement Directives

• #defInc and #defDec work only with integer values.

• Example:

  #define.Count(5)
  #defInc.Count
  print #Count;   // Outputs 6

Local Macros

• #localmacro or #macro: Used for multi-line values, often SQL or X++ fragments.

• Example:

  #macro.RetailCheck(
     %1.price == %2.price &&
     %1.itemId == %2.itemId
  )
  #endmacro

Macro Parameters

• Parameters are referenced as %1, %2, etc.

• Example:

  #macro.Compare(%1, %2)
     %1 == %2
  #endmacro

Macro Libraries

• #macrolib includes predefined sets of macros from Application Explorer.

• Example:

  #macrolib.MyAOTMacroLibrary
  

Scope

• Macros can be defined in classes or methods.

• The precompiler processes inheritance chains, so macros in parent classes are available in child classes.

📘 Example: Conditional Compilation with Macros

#define.DebugMode(1)
#if.DebugMode
    info("Debugging enabled");
#else
    info("Debugging disabled");
#endif

• If DebugMode is defined, the compiler includes the debugging message.

• This allows developers to toggle features or logging at compile time.

⚠️ Best Practices

• Avoid overusing macros: They make code harder to read and maintain.

• Prefer constants and language constructs for clarity and future compatibility.

• Use #localmacro for multi-line code fragments instead of #define.

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📖 Full details are available in the official Microsoft Learn article on Macros in X++.