[Scons-users] solving dependency cycle

[Philipp Kraus]

On 2012-08-17 12:48:09 +0200, TOM TANNER (BLOOMBERG/ LONDON) said:


> Thats not a dependency cycle per se. Please could you give us the full 

> error message, as that shows you what the cycle is between.

> 

> Also, how do you build x?


scons: *** Found dependency cycle(s):
  library/jsoncpp-src-0.5.0/src/lib_json/json_reader.cpp -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_reader.os -> 
library/jsoncpp-src-0.5.0/src/lib_json -> library/jsoncpp-src-0.5.0/src 
-> library/jsoncpp-src-0.5.0 -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_reader.cpp
  library/jsoncpp-src-0.5.0/src/lib_json/json_reader.os -> 
library/jsoncpp-src-0.5.0/src/lib_json -> library/jsoncpp-src-0.5.0/src 
-> library/jsoncpp-src-0.5.0 -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_reader.cpp -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_reader.os
  library/jsoncpp-src-0.5.0/src/lib_json/json_value.cpp -> 
library/jsoncpp-src-0.5.0/src/lib_json -> library/jsoncpp-src-0.5.0/src 
-> library/jsoncpp-src-0.5.0 -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_value.cpp
  library/jsoncpp-src-0.5.0 -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_reader.cpp -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_reader.os -> 
library/jsoncpp-src-0.5.0/src/lib_json -> library/jsoncpp-src-0.5.0/src 
-> library/jsoncpp-src-0.5.0
  library/jsoncpp-src-0.5.0/src/lib_json/json_writer.cpp -> 
library/jsoncpp-src-0.5.0/src/lib_json -> library/jsoncpp-src-0.5.0/src 
-> library/jsoncpp-src-0.5.0 -> 
library/jsoncpp-src-0.5.0/src/lib_json/json_writer.cpp


I have create a builder for downloading source.tar.gz (in short)
dw=env.Download(target.tar.gz, http://....)
extract = env.Command(dw, "extractdir", "tar ... $SOURCE")

and than I build with sources within the extract target a shared library like

env.SharedLibrary( ..., sources=[ os.join.path(str(extract), 
source1.cpp, str(extract), source2.cpp) ]

This does not work, because scons reports that the sources are not 
exists, imho I need a dependency between the
source file and the "extract-target", which I have set with Depends and 
this creates the dependency cycle error.

The parts for download and extracting works well and create a correct graph:
  +-library/jsoncpp-src-0.5.0 		//1
    +-library/jsoncpp-src-0.5.0.tar.gz
    | +-http://sourceforge.net/projects/jsoncpp/files/latest/download
    +-/usr/bin/tar

The parts for building the shared library works also well (if the 
sources exists). So I need the connection
between //1 and the env.SharedLibrary call

Thanks

Phil