[Scons-users] download builder - tips

[Philipp Kraus]

On 2013-04-06 02:41:22 +0200, Philipp Kraus said:


> thanks to Dirk and Bill for some nice email. I would like to replace my 

> "dirty hacked Scons script" to a little more general code structure and 

> would like to send them into the Scons community.

> I'm primary writing C/C++ code and uses Scons on OSX, Linux, Windows 

> (MSVC & MinGW) for the building process.

> 

> Often there exists on my C/C++ project the problem, that the project 

> uses a lot of different libraries eg LAPack, Boost, Dune-FEM .... and 

> these libs must be compiled for the project, so I use Scons for

> this building process most with a lot of env.Command code and some 

> hacked builders. With a little time, I have forked out my first "hacked 

> builder" to a more "Scons-Way-Builder".

> It is a little short builder, which downloads any URL data into a file. 

> I have pushed the builder in my repo ( 

> https://github.com/flashpixx/Storage/blob/master/Scons/site_scons/site_tools/URLDownload.py 

> )

> and a test Sconstruct under 

> https://github.com/flashpixx/Storage/blob/master/Scons/SConstruct

> This builder replaces the target on default with the filename of the 

> URL, the env setting URLDOWNLOAD_USEURLFILENAME (true | false) can be 

> enabled / disabled this target replacing

> 

> The next forked builders will be an Unpacking builder with flexible 

> tool use (eg 7-Zip under Windows, tar / gzip / bzip under *nix) and a 

> external builder for compiling extracted sources with cmake, MSVC ...


I need a little help, because I get on my builders a cyclic dependency 
on cleaning or on the second run. If I have got a "clean" directory, 
everything works fine, the download builder creates
the downloaded file and my unpack builder ( 
https://github.com/flashpixx/Storage/blob/master/Scons/site_scons/site_tools/Unpack.py 
) is run and creates the correct extracting file list.
If I run after the first run, without cleaning the builder script 
again, I get an error of the unpack builder that there exists a cyclic 
depency, an equal error is shown up, if I run "scons -c".

If I replace in the Unpack.py the line 280 (     return target, source 
) to  'return "test", source' the error does not occure, so imho the 
problem exists in the emitter. The unpack builder returns a list of 
files & directories in an archive and the download builder get the 
file. So I hope, that I can download, extract and compile the sources 
in one short step. (The unpack builder works at the moment with *nix 
systems, Windows calls are not implementated yet)

Thanks for help

Phil