For routines defined in Delphi, Tusk currently supports…

• Optional parentheses when calling zero-argument functions and procedures.
• Default parameters.
• const, var, and out.
• Open array parameters.
• Overloaded global procedures / functions.
• Interface methods (including generics).
• Overloaded interface/record methods.
• Anonymous procedures and functions.
• Low-level memory management
  (New / Dispose, GetMem / ReallocMem / FreeMem, etc).

For routines defined in Tusk, the following are supported…

• Optional parentheses.
• Default parameters.
• const, var, and out.
• Exit and Result.
• Global procedures / functions.
• Nested procedures / functions.
• Forward declared functions (for mutually recursive functions).
• Static scoping, like Delphi (not dynamic scoping, like MiniCalc).
• Anonymous procedures and functions.

In Delphi, invisible temporary managed variables are finalized when the procedure or function exits. For example…

procedure Demo; begin Writeln('Hello'); CallOnceWrapper( procedure begin Writeln('Cleanup'); end); Writeln('Goodbye'); end;

In Delphi, the above prints…

Hello Goodbye Cleanup

This is because CallOnceWrapper returns a TProc that, when its last reference goes away, calls Writeln.

In Tusk, however, invisible managed variables are finalized as soon as they're no longer needed. Thus, in Tusk, the above code prints…

Hello Cleanup Goodbye

When consistent behavior is desired, simply use an explicit variable…

procedure Demo; begin Writeln('Hello'); var Cleanup := CallOnceWrapper( procedure begin Writeln('Cleanup'); end); Writeln('Goodbye'); end;

This does not change the behavior in Delphi, but in Tusk, it ensures that the cleanup happens at the end of the procedure (matching Delphi's behavior).

Tusk doesn't yet support…

• Forward declared overloaded functions written in Tusk (Tusk functions may be overloaded or forward declared, but not both).
• Generic functions written in Tusk.
• Open array params for functions written in Tusk.
• Open array params using the out keyword.
• const [ref] parameters.
• Untyped parameters.
• array of const parameters (used by Format and related functions).
• The optional MinWidth and DecPlaces specifiers used with Write and Writeln (more details here).
• Assigning a function result using the function's name, as in… function f: Integer; begin f := 123; end; The work-around is easy: assign to Result instead.
• Passing a single value where an open array of values is required.