Was kompiliert Delphi 10.3.3 da???

[Harry Stahl]

OK, schon passiert...

[Fritzew]

Ich arbeite zur Zeit viel mit Remobjects Elements (früher mal Delphi Prism)

Die Erweiterungen die Remobjects da gemacht hat gefällt mir wirklich gut:
aus der Dokumentation: https://docs.elementscompiler.com/Ox...atements/With/
Es lohnt sich mal in die Dokumentation zu schauen .... Remobjects hat meiner Meinung nach die Sprache super aufgewertet....

Zitat:

The with can be used to temporarily introduce new members in the scope. It supports multiple with items seperated by a comma. The main benefit of with over using a regular local var declaration is that with more explicitly limits the scope of the new variables to the statement or block of statements it applies to. The do keyword can be followed by a single statement or a begin/end block grouping multiple statements.

Delphi-Quellcode:

with fb := CalculateFooBar do begin
  writeLn(fb);
end;

// fb is not available here anymore.

[Uwe Raabe]

Zitat von Fritzew:

Delphi-Quellcode:

with fb := CalculateFooBar do begin
  writeLn(fb);
end;

// fb is not available here anymore.

Wozu dann überhaupt das with , wenn man doch wieder die Variable fb benutzen muss?

In Delphi würde man das in etwa so schreiben:

Delphi-Quellcode:

  begin
    var fb := CalculateFooBar;
    Writeln(fb);
  end;
  // fb is not available here anymore.

[Fritzew]

Zitat von Uwe Raabe:

Wozu dann überhaupt das with , wenn man doch wieder die Variable fb benutzen muss?

Im Prinzip hast Du recht.... Das geht aber noch weiter:

Zitat:

When the expression for the with statement is a Record or other value type, the new variable acts as an alias to toe original record, and any changes done on the identifier will directly affect the original record.

By contrast, assigning the record to a new local var declaration would create a copy opf the record on the stack:

Delphi-Quellcode:

var x: Person;
x.Name := "Peter";

with y := x do  
  y.Name := "Paul";
  
// x.Name is now Paul

Compared to:

Delphi-Quellcode:

var y := x;
y.Name := "Paul";

// x.Name is unchanged, as y is a separate copy