* Cosmetic changes:

[gdcm.git] / DEVELOPPER

diff --git a/DEVELOPPER b/DEVELOPPER
new file mode 100644 (file)
index 0000000..f4fb12f
--- /dev/null
+++ b/DEVELOPPER
@@ -0,0 +1,46 @@
+The following comments are intended for core gdcm developpers.
+
+
+* Python related section.
+  Depending on the automake/autoconf/autogen.sh flags you used gdcm could
+  be wrapped in two ways:
+  - the first python wrappers of gdcm use Swig (http://www.swig.org). They
+    are the ones generated when using autogen.sh --enable-python. 
+    The entry point is here the file gdcmPython/gdcm.i which uses the
+    Swig synthax. As the last lines of this file (the ones starting
+    with the %include directive) only some classes are wrapped for python.
+    In theory only the library interface (basically the classes gdcmHeader
+    and gdcmFile) should be wrapped, but the time being some additional
+    classes are added (just to make sure those classes are Swig compatible:
+    swig is here used as some lint checker!?).
+    Since gdcm is written in C++, Swig will produce two different outups:
+      -- some C based low level wrapper (see gdcmPython/gdcm_wrap.c)
+      -- some Python based object oriented so called "shadow classes" (see
+         file gdcmPython/gdcm.py)
+    We also added the file gdcmPython/__init__.py which is the one that
+    actually gets loaded when ones uses the gdcmPython Python package.
+    The file __init__.py loads the swig generated shadow classes (gdcm.py)
+    but will only re-export the interface of gdcm which correponds to
+    the lines :
+       gdcmHeader = gdcm.gdcmHeader
+       gdcmDictSet = gdcm.gdcmDictSet
+       gdcmFile = gdcm.gdcmFile
+    Hence this whole Swig wrapping process is quite odd since we shall
+    wrap more classes (%include in swig.i) than eventually exported to
+    the final user by gdcmPython/__init__.py.
+  - the second python wrappers use the vtk (http://public.kitware.com/VTK/)
+    native wrappers i.e. the binary vtkWrapPython. But it should be noticed
+    that the purpous is here a bit different than the one of the Swig
+    generated Python wrappers. When using vtkWrapPython the goal is to
+    wrap a single vtk class namely vtkGdcmReader as defined in files
+    in vtk/vtkGdcmReader.h vtk/vtkGdcmReader.cxx (and of course those
+    files are hand made vtk oriented wrappers of gdcm).
+    Those wrappers are the one generated when using
+       autogen.sh --enable-python --enable-vtk
+  - In order to understand the difference between both wrappers you should 
+    compare both demo scripts gdcmPython/demo/vtkGdcmDemo.py and
+    gdcmPython/demo/vtkGdcmReader.py. The first one only uses the
+    Swig wraped classes ("from gdcmPython import gdcmHeader') as opposed
+    to vtkGdcmReader.py which also uses vtkWrapPython wraped classes
+    ("from gdcmPython.vtkgdcmPython import *").
+