On 19/9/2011 08:19, Paul Ishenin wrote:
19.09.2011 20:05, Hans-Peter Diettrich wrote:
IMO the use of RawByteString will not help much, except for
(possibly) simpler code and less overloaded procedures. Avoiding
implicit conversions instead will require *fixed* string types and
encodings, for different tasks with different needs. E.g. a TFileName
string type will allow to eliminate all conversions, when a string is
known to hold file or path names (by design). Likewise an LCLString
(widget, component) type could do the same for the LCL widgetset
interface. The FPC decisions about string container classes
(TStrings...) will tell where to put the break line, between user and
widget string types.
My statement about RawByteString need to be read in the context of
code where I replaced UTF8String to AnsiString.
Just to point that RawByteString should be used in very specific cases
like stated in the link below
http://stackoverflow.com/questions/498315/delphi-2009-rawbytestring-vagaries
Regarding change to UTF8ToUTF16 function RawByteString should not be used.
function UTF8ToUTF16(const S: UTF8String): UTF16String;
Currently does not matter if is UTF8String or AnsiString, but when the
new string type starts to be used, there's no problem using UTF8String.
In fact the use of UTF8String will be necessary otherwise explicit
conversions with extra hidden temporary variables inside the function
will be necessary as is the case with RawByteString.
Also PChar should be changed to PAnsiChar since PChar can point to a
word (UTF16 RTL) or a byte (UTF8 RTL)
I explained in a mail in the devel list (where you see UnicodeString
read as UTF8String)
I'm talking about:
function FileGetAttr(const FileName: UnicodeString): Longint;
begin
Result:=Integer(Windows.GetFileAttributesW(PWideChar(FileName)));
end;
Inside the procedure there will be no conversion since is already
UTF16, just a typecast to PWideChar which in fact is a function
The conversion will be done before the function call only if
necessary (eg UTF8 -> UTF16). The decision to convert or not is done
at compiler time.
With RawByteString
function FileGetAttr(const FileName: RawByteString): Longint;
begin
Result:=Integer(Windows.GetFileAttributesW(PWideChar(UnicodeString(FileName))));
end;
Here the decision to convert or not is done at runtime by checking the
CodePage of FileName. Also there's one more temp variable due to
UnicodeString typecast.
In summary:
With UnicodeString decision to convert at design time
With RawByteString decision to convert at run time + one more temp
variable
Luiz
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