Inline declarations: var vs const

Question

When I use inline declarations, should I prefer const over var?

In all online examples, and even in Delphi's own documentation, I see that var is being used. However, I think that const often better expresses my intentions, and prevents accidental modifications.

Small example to demonstrate what I mean:

{$APPTYPE CONSOLE}

program VarVsConst;

uses
  Spring.Collections,
  System.SysUtils;

function UsingVar:string;
begin
  var dict := TCollections.CreateDictionary<string, Integer>;
  dict.Add ('one', 1);
  var pair := dict.ExtractPair('one');
  Result := pair.Value.ToString;
end;

function UsingConst:string;
begin
  const dict = TCollections.CreateDictionary<string, Integer>;
  dict.Add ('one', 1);
  const pair = dict.ExtractPair('one');
  Result := pair.Value.ToString;
end;

begin
  Writeln(UsingVar);
  Writeln(UsingConst);
  Readln;
end.

So, are there any downsides or dangers to the UsingConst implementation?

Answer 1

I suppose a downside could be that a program is more easily "hacked" into. It's a static value. Not sure how much more of a downside when you've got a var assignment like str := 'password' but you get the idea, this is more of an "in general" const opinion. In your example I really don't see a difference as far as this goes, but there are people smarter than me who could spot it if there.

I like const, once it's assigned you can't fubar things accidentally. If I'm that worried about a hack I can change things after the fact, closer to release.