Re: [Boost-users] Newbie Jamfile author question

From: Rene Rivera (grafikrobot_at_[hidden])
Date: 2006-09-13 16:57:08

Drumheller, Michael wrote:
> Hello:
> 
> I am trying to write some Jamfiles and I am finding that bjam tends to
> run my rules twice.
> Here is a tiny demo (using Boost 1.31.1 on Windows XP, with zsh/cygwin,
> bjam version
> "3.1.13. OS=NT".).
> 
> % export BOOST_ROOT=c:/boost_1_33_1; cd c:/; rm -rf deleteme; mkdir
> deleteme; cd deleteme; echo 'Echo Hello Twice ;' > Jamfile; bjam
> Hello Twice
> Hello Twice
> ...found 8 targets...
> 
> (Note:  If the first statement is "export BOOST_ROOT=;" instead, I get
> the error "Unable to
> load Boost.Build: could not find "boost-build.jam...Attempted search
> from c:\deleteme up to
> the root...etc.") 
> 
> Notice the double-execution. 

> Can anyone reproduce and/or explain this?

Yes, that's per design of the build system (v1 only). It uses the first 
pass to declare all the targets, and the second pass to define them and 
hence to possible refer to other declared targets.

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