I have an enumerated type and I need to pass an array of this type as parameter:
type
TTest = (a,b,c);
procedure DoTest(stest: TArray<TTest>);
When I compile
DoTest([a]);
I receiv the error below:
Error: E2010 Incompatible types: 'System.TArray' and 'Set'*
So, how can I call DoTest without creating a variable of type TArray<TTest>?
I don't have a Delphi compiler available right now, so I cannot verify this, but to me
procedure DoTest(stest: TArray<TTest>);
doesn't declare stest as an open array parameter, but a dynamic array parameter. You do want
procedure DoTest(const stest: array of TTest);
One way to do what you want is to change the parameter to an open array of TTest, i.e.
procedure DoTest(const stest: array of TTest);
But supposed you don't want to change the parameter, and really want it to be a TArray<TTest>, then you can simply use the array pseudo-constructor syntax to call it (in almost all versions of Delphi, except the very old ones). Say you have something like:
type
TTest = (a, b, c);
procedure DoTest(const stest: TArray<TTest>);
// simple demo implementation
var
I: Integer;
begin
for I := Low(stest) to High(stest) do
Write(Integer(stest[I]), ' ');
Writeln;
end;
Then it can be called, using the Create syntax without having to declare a variable or having to fill it manually. The compiler will do this for you:
begin
DoTest(TArray<TTest>.Create(a, c, b, a, c));
end.
The output is, as expected:
0 2 1 0 2
The compiler may confuse a with another declaration.
Qualify the type like this:
DoTest([Ttest.a]);
Note:
This feature of initializing dynamic arrays was introduced in XE7.
DoTest without creating a variable of type TArray<TTest>?"TArray<TTest>?. My answer works well in XE7+ and initializes a dynamic array.I'm assuming that with "how can I call DoTest without creating a variable of type TArray" you want to avoid declaring and initializing local variable, ie code like
var arr: TArray<TTest>;
begin
SetLength(arr, 1);
arr[0] := a;
DoTest(arr);
For this you can use the array constructor like:
DoTest(TArray<TTest>.Create(a));
This syntaxs is supported at least since Delphi 2010.
DoTest without creating a variable of type TArray<TTest>?"
TArray<Ttest>is not an open array parameter -array of Ttestwould be.TArray<TTest>. How can I call it without passing aTArray<TTest>?" Surely it's obvious that you cannot do that. Change the function to accept an open array parameter.