Best practices for deprecation of AL code

This article provides guidelines that describe how code in the Base App is obsoleted. The article describes some best practices that Microsoft is using for obsoleting code, and is meant as a nonenforced guidance and best practice. You can use this article as an inspiration on how to set up a best practice for your own code. For obsoleting code, preprocessor statements in AL can be used. For more information, see Directives in AL.

Obsoleting code

When we obsolete code, we:

• Add the preprocessor statements #if, #else, and #endif surrounding the code to be obsoleted.

• Use one of the following preprocessor symbols, where the pattern is CLEAN<Version>, such as CLEAN15, CLEAN16, CLEAN17, and CLEAN18.

  Note

  These symbols aren't shipped with the product.

• For tables and fields, we also use CLEANSCHEMA in a second phase to delete the SQL schema.

• The version to use in the symbol matches the <major> of the ObsoleteTag. For example:

  • If a method is to be removed, then we use #if not

    #if not CLEAN18
        [Obsolete('Replaced by SetParameters().', '18.0')]
        procedure SetParams(NewAnalysisArea: Option Sales,Purchase,Inventory; NewReportName: Code[10]; NewLineTemplateName: Code[10]; NewColumnTemplateName: Code[10])
        begin
            SetParameters("Analysis Area Type".FromInteger(NewAnalysisArea), NewReportName, NewLineTemplateName, NewColumnTemplateName);
        end;
    #endif
    

  • If an action is to be removed, then we also use #if not

    
    #if not CLEAN17
        action("Social Listening Setup")
        {
            ApplicationArea = All;
            Caption = 'Social Engagement Setup';
            RunObject = page "Social Listening Setup";
            Visible = false;
            ObsoleteState = Pending;
            ObsoleteReason = 'Microsoft Social Engagement has been discontinued.';
            ObsoleteTag = '17.0';
        }
    #endif
    

  • If a table or table field is to be removed, then we use #if #else #endif

    
    #if not CLEANSCHEMA19
    table 1808 "Aggregated Assisted Setup"
    {
        Access = Internal;
        Caption = 'Aggregated Assisted Setup';
    #if CLEAN16
        ObsoleteState = Removed;
        ObsoleteTag = '19.0';
    #else
        ObsoleteState = Pending;
        ObsoleteTag = '16.0';
    #endif
        ObsoleteReason = 'Data available in Assisted Setup already- extensions also register in the same table.';
    }
    #endif
    
    

    #if not CLEANSCHEMA20
    field(11701; "Bank Account No."; Text[30])
    {
        Caption = 'Bank Account No.';
        Editable = false;
    #if CLEAN17
        ObsoleteState = Removed;
        ObsoleteTag = '20.0';
    #else
        ObsoleteState = Pending;
        ObsoleteTag = '17.0';
    #endif
        ObsoleteReason = 'Moved to Core Localization Pack for Czech.';
    }
    #endif
    

  • If a table is to be marked as Temporary, then we use #if #else #endif

    
    table 5503 "Acc. Schedule Line Entity"
    {
        Caption = 'Acc. Schedule Line Entity';
        // TableType = Temporary;
    #if CLEAN17
        TableType = Temporary;
    #else
        ObsoleteState = Pending;
        ObsoleteReason = 'Table will be marked as TableType=Temporary. Make sure you are not using this table to store records';
        ObsoleteTag = '17.0';
    #endif
    

In order to have the compiler take the new ‘clean’ code path, symbols must be defined. The symbols are defined in the app.json file with the following setting. For more information, see JSON Files.

"preprocessorSymbols": [ "CLEAN15", "CLEAN16", "CLEAN17", "CLEAN18" ]

Important

A best practice is to change this locally to make sure everything compiles, run tests locally, and then submit test jobs.

Fixing code when objects are removed

If an action or other code element points to a now removed object, then the guidance is to:

• Ensure that the action is obsoleted.
• Add preprocessor statements to fix the issue.
  • If code points to an obsoleted method, then use directives to put in the fixed code.
  • If code points to an obsoleted table/field, then use directives to put in the fixed code.

Related information

AL development environment
Directives in AL
Microsoft timeline for deprecating code in Business Central
ObsoleteTag property
ObsoleteState property
ObsoleteReason property
Obsolete attribute