[Qt5-feedback] Build system requirements for Qt5

[Thiago Macieira]

Em Friday, 3 de June de 2011, às 13:59:20, Charley Bay escreveu:
> Marcus spaketh:
> > I have been considering this for quite some time, and we have been
> > talking about this at Kitware. There is discussion of replacing Qt's
> > build system, possibly writing a new one or modifying an existing one.
> > What I would really like to know is what you want the declarative
> > language to look like. Is the general consensus a JSON structure?
> > Would looping and conditional constructs from JavaScript be used, or
> > purely the data container format?

The most important thing is that it be a declarative language, not imperative. 
It needs to be something that the IDE can fully parse without ambiguity and 
without hacks as "evaluate all branches of if-else to true".

It should be clear which parts are related to the configuration-detection part 
of the cycle and which ones list the build instructions. Like autoconf and 
automake do: autoconf is imperative, automake is declarative.

I'm not going to mention requirements that cmake already addresses, like the 
ability to detect existing software components installed, read files, search 
for files, etc. It also needs to do deployment of files (which cmake does), 
cross-compilation and create target packages -- or be able to generate the 
data for the package creation mechanism, such as file listing.

So, to answer your question on JSON: yes, it's probably a good format for 
storing data, but it's not really human-friendly. Something more human-
friendly (*cough* QML *cough*) would be nicer. Loop structures should not 
exist; conditionals should be a feature of the declarative language. In other 
words, for the case of JSON: it's just JSON, not JavaScript. So you'd have to 
store everything in the data container format.

> <
> http://labs.qt.nokia.com/2009/10/12/to-make-or-not-to-make-qmake-and-beyond/
> 
> 
> ...and the next-day follow-up:
> 
> <
> http://labs.qt.nokia.com/2009/10/14/to-make-or-not-to-make-qmake-and-beyond-
> redux/

Those are still relevant.

> That was before QML/Javascript was really "prime time", so I'd guess yes,
> you'd probably be ok thinking about a JSON/Javascript syntax, since it was
> "sort of supported" in those threads, and I'd guess no less supported as a
> preferred direction now.

See above.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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