[PATCH ipmi-fru-parser] RFC: use cmake.

[Patrick Williams]

Joel,

On Mon, Mar 07, 2016 at 02:30:51PM +1030, Joel Stanley wrote:
> On Fri, Mar 4, 2016 at 9:00 AM, OpenBMC Patches
> <openbmc-patches at stwcx.xyz> wrote:
> > From: Patrick Williams <patrick at stwcx.xyz>
> >
> > There was a previous proposal to consider autotools (see
> > openbmc/ipmi-fru-parser#7).  This is an alternative implementation
> > using cmake.
> 
> I'm not a fan of autotools; I have not chosen to use it on small
> projects in the past.
> 
> That said, I have stopped working on projects due to cmake's
> downsides. It's overly complex, and no clear way to implement rules,
> making it hard for newbies and experienced developers alike.

Can you elaborate on this?  I honestly don't have much experience with
CMake but from the little I have played with it it seems 5x easier than
makefiles (which autotools still use via Makefile.am).

Compare the gigantic m4 script required to test C++14 support in
autotools vs two lines in CMake:
    set(CMAKE_CXX_STANDARD 14)
    set(CMAKE_CXX_STANDARD_REQUIRED on)

> I would prefer to see autotools implemented by one of our team members
> that has experience with it, and they can help the rest of us maintain
> it.

It isn't just a one-repository thing though.  What is going to happen is
that even a well-written autotools is going to get copied and modified
and copied and modified into all the various openbmc repositories.
We're going to need a few autotools experts to keep watch over
everything and avoid hit-by-bus situations.

> 
> I noticed in my feeds a new project created by some of the Xorg
> developers that is a nice example of a clean, well structured project
> that uses systemd, dbus, and autotools can be found here:
> 
>  https://github.com/libratbag/ratbagd
> 

That example has a 290 line m4 script, 160 line configure script, and a
100 line makefile just to build an executable out of 6 .c files.  Even
if it is "clean" there is way too much to consume here.
    
The "meat" of the dependency description is in these lines:
    PKG_CHECK_MODULES([LIBUDEV], [libudev])
    PKG_CHECK_MODULES([LIBSYSTEMD], [libsystemd >= 227])
    PKG_CHECK_MODULES([LIBRATBAG], [libratbag >= 0.2])

CMake has a similar macro via 'find_package'.

> Cheers,
> 
> Joel
> 
-- 
Patrick Williams
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