On 15/06/2020 15:37, Alex Peshkoff via Firebird-devel wrote:
On 2020-06-11 18:30, Tony Whyman wrote:
On 11/06/2020 11:18, Pavel Cisar wrote:
This is not a problem for languages like Python, Java and .NET that
don't use these files at all, but C++ & Pascal are still important
languages and we should offer some better solution. At least it
should be discussed with those who use them (for example MWA
Software, developer of ibx4lazarus?).
Did I just hear my name mentioned ;)
My main gripe with the new API is really more about documentation
than anything else. It is not easy to work out how to use it except
by experimentation. E.g. with the new DecFloat type I basically had
to look at how the interface returned the BCD format value by using
the debugger to inspect the data at the byte level and then work out
how to convert this (unpacked) format into the packed tBCD record
used by FPC and Delphi - and vice versa.
That's format present in original IBM's library. They do not support
packed BCD. If you provide a link to the description of packed BCD I
can add support for it.
I was more concerned about documenting (or providing a reference to the
documentation) for the BCD format used by the Firebird Client API. When
it comes to the packed BCD format used by Delphi and FPC, there seems to
be little more than the source code in the FmtBCD unit - and they are
not even consistent in the way that the precision is recorded.
I still don't know how to process an INT128 type except by converting
it to a string (!) and then parsing the string.
It's compatible with __int128 from gcc. Sorry, I do not know how to
explain it in pascal way.
Well, that gives me a pointer.
The "firebird.pas" file is always "processed" before it is taken into
IBX for Lazarus - which is perhaps why I am less bothered about any
imperfections in the source code. The most important need for this is
to extract the type and const declarations and separate them out in
order to avoid name space conflicts between the actual API and IBX,
as well as to limit pollution of the global name space. I also remove
the exceptions generated by the cloop code as I prefer to handle the
exceptional conditions in IBX itself.
An ability to process exception in another way is very important but
missing. Can you suggest a generic way? If yes suppose we can add it
to code generator.
Here's a simple example of what I have done:
function IMaster.getMetadataBuilder(status: IStatus; fieldCount:
Cardinal): IMetadataBuilder;
begin
Result := MasterVTable(vTable).getMetadataBuilder(Self, status,
fieldCount);
{$IFDEF USEFBEXCEPTION}FbException.checkException(status);{$ENDIF}
end;
I have made every call to FbException.checkException conditional - in
practice, IBX never defines USEFBEXCEPTION and hence these calls are
commented out. The IBX code will typically check the status itself and
raise its own exception when necessary. There are some exceptions e.g.
when creating an attachment, IBX looks at the error code and may perform
an alternative e.g. if the database does not exist then it may be created.
Is it really necessary to perform exception handling in firebird.pas?
The user can either do their own exception handling or call
FbException.checkException to perform default exception handling.
The call to get the IMaster interface also assumes static linking
with the client library,
???
Why?
The syntax
function fb_get_master_interface : IMaster; cdecl; external 'fbclient';
is usually used for static linking. I believe that it can be used with
dlls - but you have no control over the location. You just get the first
one it finds in the path.
while IBX always dynamically loads the fb client library and then
dynamically links to each exported call using GetProcAddress.
fb_get_master_interface() is absolutely same call as all others in
fbclient, I do not understabd your problems with use of it in
GetProcAddress. At least it's posix analogue dlsym() works fine.
I am really just making the point that the call to
fb_get_master_interface in firebird.pas is really little more than a
simple example of how to load the firebird client library. For anything
more than basic use this has to be commented out as it will conflict
with dynamic library loading.
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