On 29/11/2007, Joseph Kowalski <jek3 at sun.com> wrote: > Stefan Teleman wrote: > > > > > > Joseph Kowalski wrote: > > > >> As I recall, I thought we were supporting this multiple versions of > >> "Apache, MySQL, PHP" at the level they assert to be compatible. > >>> Considering the fact that Trolltech is orders of magnitude better at > >>> maintaining compatibility than either of those above. > >> That's good to hear, but that doesn't address the question. The > >> question is "Does Trolltech respect upwards compatibility below the > >> Major release level (ie: QT3 -> QT4)?". If the answer is "yes", then > >> Whoopie! If the answer is "no", we need to look further into this. > > > > Official answer to this question from Trolltech: > > > > <QUOTE> > > I checked with Qt support experts here in Redwood City and they > > confirmed that Qt4.x is forward binary compatible with previous > > versions, i.e. a program written for Qt4.2 will run with no problem on > > subsequent Qt4.2+n releases. (f.ex. Qt4.3 and Qt4.4). However, a Qt4.4 > > program will not necessarily automatically runs on Qt4.3 or Qt4.2, > > especially if the new program takes advantage of newer functionality of > > a later release. > > > > The compatibility is at major release level, i.e. 4.x and so all > > sub-releases like 4.x.y are compatible as well, obviously. > > </QUOTE> > > > > --Stefan
I would add to that this little snippet: [quote] Qt is backwards binary and source compatible within each major release. This means that a program linked dynamically to e.g Qt 3.1.1 will continue running with Qt 3.3.5 without the need to recompile. Qt is not binary compatible between major versions such as Qt 2.x, Qt 3.x and Qt 4.x etc. Qt is also not forwards compatible, meaning that applications created with a newer version of Qt will not necessarily run or compile against older Qt versions. [/quote] http://trolltech.com/developer/knowledgebase/560/ and this one: [quote] 8. Qt breaks binary compatibility from version to version. Will such a user-level inconvenience continue to be the case in the future and what can it be done to avoid it? Harri Porten: Binary compatibility has only been broken two times in Qt's history. Namely when switching to major version 2 and 3, respectively. In between those shifts - the last one happened more than two years ago - we have invested major efforts to keep compatibility between minor releases. This mostly involves a robust class design and educating every developer about the technical rules to obey [/quote] http://www.osnews.com/story.php/259/Interview-with-TrollTechs-Harri-Porten/ -- Shawn Walker, Software and Systems Analyst http://binarycrusader.blogspot.com/ "We don't have enough parallel universes to allow all uses of all junction types--in the absence of quantum computing the combinatorics are not in our favor..." --Larry Wall
