[fpc-pascal] Re: linux: should we hard-code versioned or unversioned shared libraries in our apps?

Michael Van Canneyt michael at freepascal.org
Wed Aug 15 16:19:56 CEST 2012

On Wed, 15 Aug 2012, Reinier Olislagers wrote:

> On 15-8-2012 15:59, Graeme Geldenhuys wrote:
>> Hi,
>> On 15 August 2012 14:39, Jonas Maebe <jonas.maebe-3RqwKoEL1alVsUKGZV2E3Q at public.gmane.org> wrote:
>>>> FCL-DB uses dynamic linking by default, and looks for the unversioned
>>>> shared library. So what specific Firebird version is the FCL-DB coded
>>>> too?
>>> I have no idea, which is why I also said in my first reply:
>> Umm, so ideally the ibconnection.pp unit should really be split into
>> various units with version numbers in their names. That way we will
>> know to which Firebird version they are referring too.
>> eg:   ibconnection.pp   // old interbase only (eg: Delphi 7)
>>         firebird-1.x.pp
>>         firebird-2.1.pp
>>         firebird-2.5.pp
>> Include files could probably be used to reduce some duplication of code.
> OT: that would be useful for another reason.
> Firebird 3 will introduce the BOOLEAN datatype and other innovations
> (encrypted connections, etc).
> Interbase has had BOOLEAN support for a while now.
> It would be nice to be able to support new functionality without
> sacrificing the ability to connect to older clients.

That has nothing to do with dyn versus static linking.

You can perfectly detect which library version you are loading, 
and enable/disable certain functions based on this.

Mysql is a different story in that the internals of the structures 
change with each release, making it almost impossible to unite all 
versions in 1 unit.

Firebird has a long tradition of keeping the API and structures 
backwards/forwards compatible, thus obliviating the need for 
different units for each version.

At least for firebird, there will be 1 unit, loading dynamically what 
is available. If you want to load something else than the default, 
you have been able to do so since day 1.

Contrary to Marco's belief, I am firmly convinced that this is the 
best and easiest approach.


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