A. Short summary of the problem:
type
A = class(TObject)
end;
B = type A;
The compiler error E2010 incompatible types: 'B' and 'A'
is shown, when you instantiate a variable of class B in the following style:
var
TheB: B;
begin
TheB:= B.Create;
..
I can avoid that problem by removing the second "type", so the declaration is the standard one:
type
A = class(TObject)
end;
B = A;
But in my opinion, the error should not come, even WITH the second "type", because A is not directly used (The second "type" tells the compiler to see both classes as individuals, see http://docwiki.embarcadero.com/RADStudio/Seattle/en/Declaring_Types for details). Can someone explain, because of what reason the error ignores my opinion? (o;
B. Complete history and more complex details:
First of all: The error:
[dcc32 Fehler] gboDHL.pas(165): E2010 Inkompatible Typen: 'Origin' und 'CountryType'
(which means "incompatible types" in english),
occurs in the following line of code:
AShipmentOrder.Shipment.Shipper.Address.Origin:= DHL_geschaeftskundenversand_api_2.Origin.Create;
Now here is the background:
I try to communicate with the "new" DHL Geschäftskundenversand API v2.2 which still uses SOAP to create a shipment order. DHL_geschaeftskundenversand_api_2
is the completely generated unit from the integrated delphi xe7 WSDL generator for that service.
AShipmentOrder
is the instance which represents the top level xml node of the request.
The class "Origin" is implemented/generated this way:
type
CountryType = class(TRemotable)
private
Fcountry: country2;
Fcountry_Specified: boolean;
FcountryISOCode: countryISOType;
Fstate: state;
Fstate_Specified: boolean;
Fcountry_: country;
Fcountry__Specified: boolean;
FcountryISOCode_: countryISOType;
Fstate_: state2;
Fstate__Specified: boolean;
procedure Setcountry(Index: Integer; const Acountry2: country2);
function country_Specified(Index: Integer): boolean;
procedure Setstate(Index: Integer; const Astate: state);
function state_Specified(Index: Integer): boolean;
procedure Setcountry_(Index: Integer; const Acountry: country);
function country__Specified(Index: Integer): boolean;
procedure Setstate_(Index: Integer; const Astate2: state2);
function state__Specified(Index: Integer): boolean;
published
property country: country2 Index (IS_OPTN) read Fcountry write Setcountry stored country_Specified;
property countryISOCode: countryISOType read FcountryISOCode write FcountryISOCode;
property state: state Index (IS_OPTN) read Fstate write Setstate stored state_Specified;
property country_: country Index (IS_OPTN) read Fcountry_ write Setcountry_ stored country__Specified;
property countryISOCode_: countryISOType read FcountryISOCode_ write FcountryISOCode_;
property state_: state2 Index (IS_OPTN) read Fstate_ write Setstate_ stored state__Specified;
end;
Origin = type CountryType; { "http://dhl.de/webservice/cisbase"[GblElm] }
The "property" Origin of AShipmentOrder.Shipment.Shipper.Address
is implemented/generated this way:
type
NativeAddressType = class(TRemotable)
...
published
...
property Origin: Origin Index (IS_OPTN or IS_REF) read FOrigin write SetOrigin stored Origin_Specified;
...
end;
If it is unclear, let me say, that ´AShipmentOrder.Shipment.Shipper.Address´ is of class NativeAddressType
I'm using Delphi XE7 on Windows 10, 64bit, compiling to 32bit.
The delphi WSDL generator has different problems, which I had to manage before, and it is really not "nice" that in the output the property names are identical to the class names, but that is not changeable, it seems. The class "Origin" is not the only class in that generated unit which is named as the property it belongs to, but the error only occurs, when such a class is implemented as
type
A = type B
I tried to find a description of that special declaration variant, but that is quite hard, because the keywords are too often used.
On http://www.delphibasics.co.uk/RTL.asp?Name=Type I found the following explanation:
1.type Name = Existing type
Refers to an existing type, such as string by a new Name.
2.type Name = type Existing type
This has the same effect as above, but ensures that at run time, variables of this type are identified by their new type name, rather than the existing type name.
If I understand that correctly, that means that in my example the class Origin
is not identified anymore as CountryType
, but as Origin
. That should be fine, because the property Origin
is declared as to be of class Origin
.
While going on to try to understand that problem, I manually renamed The class "Origin" in the generated unit to OriginType (delphi used that postfix "Type" with several other classes in that unit, not clear, why it has not used it with the Origin-Type). After that, I can exclude a name-conflict, because now the error is
[dcc32 Fehler] gboDHL.pas(165): E2010 Inkompatible Typen: 'OriginType' und 'CountryType'
There seems to be no reason because of what that error occurs.
After some hours without some ideas I found this Embarcadero WIKI entry: http://docwiki.embarcadero.com/RADStudio/Seattle/en/Declaring_Types
After reading and thinking about that, I understood, that the "type" in A = type B
is not necessary in that case, because there is no need to handle class A in another way than class B, so I removed that manually in the generated unit and now, it works fine.
I also understand, that a special option in the generator was checked to prevent "name conflicts". If this option is not checked, this problem also should be solved (but maybe some others come around (o; ).
Maybe this helps someone to spent more time outside than with a problem like that (o;
But in the end, I do not understand what was the problem here, because all properties were of type "Origin" and later of "OriginType", also this type was created with Origin.Create
and later with OriginType.Create
. So the "CountryType" was never used, except for the class declaration of "Origin" / "OriginType". In my opinion this should not lead to that problem, but it does.
Can somebody explain that?
Thank you in advance
Kai