[fpc-pascal] Strings - suggestions

[Michael Van Canneyt]

On Sat, 22 Dec 2012, dev.dliw at gmail.com wrote:

> Hi,
> thanks for the quick reply.
>
> So the direction seems to be quite clear...
> ... unfortunately this seemingly wasn't communicated clearly enough to the
> surroundings.
>
>> Because of the requirement for backwards compatibility with FPC itself,
>> we'll make 2 RTLs: one backwards compatible, one with the new unicode string.
> Do you mean really seperated sources or a comiler switch?

A bit of both :-)

>
> What's the problem to use the "new" RTL with Ansistring? I can't see a
> problem, if it doesn't use direct string access...

For obvious reasons, the RTL uses direct string memory access in many places.

> ... of course you have to compile it accordingly..

You can use ansistring, no problem.

The problem are classes. If I define

TComponent = Class(TPersistent)
Published
   Property Name : String;
end;

Then name will be of the string type as declared in the unit where TComponent is defined. 
For properties this is not so much of a problem but if you try to override something like

Procedure(Arg : String); virtual;

Then the string type must match the original string type as in the original declaration, 
no matter what the string type in your particular unit.

>> so you can choose which string type you need per unit
> Can a project wide choice override this for *any* unit (3rd party) or will
> there be conversion going on between the different units?

There will always be conversion if
1) a unit specifies a string type by itself.
2) the unit comes in compiled form.

Michael.