[CMake] Newbie questions

[Jeff Squyres]

Greetings!

We are considering changing a relatively large software project away 
from the GNU tool suite (Autoconf, Automake, Libtool), and cmake was 
suggested to us.  I've downloaded it, played with it a little bit, read 
through the documentation and FAQ, and have looked through the last 
month or two of activity here on the mailing list.  It is my impression 
that cmake replaces these three tools by doing per-system tests, 
traversing directories, compiling source files, and building libraries 
and applications.  It does this by analyzing all the CMakeList.txt 
files and emitting "native" build instructions (such as VC++ projects, 
makefiles, etc.).

Needless to say, I'm still quite the cmake newbie.  I hope that this is 
the appropriate forum to ask some newbie questions -- please feel free 
to redirect me to documentation, old posts on the lists, or other 
places that I can just got RTFM and not bother people about them.  I 
didn't see these questions answered, but it's quite possible that I 
missed them somewhere:

1. Similar to some prior posts, we have a large software library that 
is built up from a large number of subdirectories (a whole tree of 
subdirectories, actually).  With Automake/Libtool, we build one library 
per directory and then "roll them up" into One Big Library at the end 
(so that the user does "-lWholeShebang", as someone previously posted 
here).

I don't actually care about making a library in each subdirectory (we 
only do that because it is The Automake/Libtool Way), but being able to 
invoke "make" in each subdirectory is quite a useful thing.  What is 
the canonical cmake way having lots of source files dispersed 
throughout an entire tree (some of which may be conditionally compiled, 
depending on architecture, etc.) compiled into a single, top-level 
library?

2. Automake provides two extremely useful targets that I don't see 
supported in cmake: "uninstall" and "dist".

2a. Since "install" is supported, would it be difficult to implement 
"uninstall"?

2b. "dist" is also quite useful -- it rolls up all the source files 
that it knows about (and any additional files like README that you can 
tag to be included) and makes a perfect tarball suitable for 
distribution (ensuring all the permissions are correct, vim/emacs 
backup files are excluded, etc.).

Are there any plans to support a "dist"-like target that makes a 
tarball suitable for distribution?

3. Waving my hands and assuming that I can somehow make a tarball that 
I can distribute to users, do the users need to have cmake installed to 
build it?  It's not 100% clear to me from reading all the docs and 
whatnot.  For example, if I run "cmake" on my development tree (such 
that it makes makefiles) and tar that up, is that suitable for users 
with a wide variety of POSIX platforms?  More specifically: when I run 
"cmake", does it make a configuration for *that specific machine*, or 
is it suitable for any machine that supports "make"?

For example, our code needs to know if the system natively supports 
asprintf().  If it does, a #define zeros out a bunch of our code; if it 
doesn't, that #define activates a bunch of things in our code.  If I 
run "cmake" and tar up the results on a machine that supports 
asprintf(), what happens if someone untarrs and runs "make" on a 
platform that doesn't?

Even more specifically: with my userbase, I cannot guarantee that they 
will have cmake installed.  Indeed, it is highly likely that they will 
not.  One of the nice things about the GNU tools is that users don't 
need to have Automake/Autoconf/Libtool installed to build an 
Automake/Autoconf/Libtool-produced tarball.  Is the same true with 
cmake?

4. How good is cmake's support for shared libraries?  One of the main 
reasons we use Libtool is because it knows how to build shared 
libraries for a *lot* of different compilers on *lots* of different 
systems (including the wide variety of compilers available for the 
Linux platform).  What platforms / compilers does cmake support 
building shared libraries for?

-----

Many thanks for your time.

-- 
{+} Jeff Squyres
{+} The Open MPI Project
{+} http://www.open-mpi.org/