Add parameter callback_begin when generating the documentation (#358)

* Add parameter callback_begin

_doc/sphinxdoc/source/conf.py

@@ -11,14 +11,20 @@
 sys.path.insert(0, os.path.abspath(os.path.join(os.path.split(__file__)[0])))
 from pyquickhelper.helpgen.default_conf import set_sphinx_variables
 
+
+def callback_begin():
+    print("[sphinx.conf.py] documentation started.")
+
+
 set_sphinx_variables(__file__, "pyquickhelper", "Xavier Dupré", 2021,
                      "alabaster", alabaster.get_path(),
                      locals(),
                      github_repo="https://github.com/sdpython/pyquickhelper.git",
                      extlinks=dict(issue=(
                          'https://github.com/sdpython/pyquickhelper/issues/%s',
                          'issue ')),
-                     link_resolve="http://www.xavierdupre.fr/app/")
+                     link_resolve="http://www.xavierdupre.fr/app/",
+                     callback_begin=callback_begin)
 
 # there is an issue with this attribute on Anaconda math_number_all
 assert math_number_all or not math_number_all

src/pyquickhelper/helpgen/default_conf.py

@@ -19,7 +19,7 @@ def set_sphinx_variables(fileconf, module_name, author, year, theme, theme_path,
                          sharepost="facebook-linkedin-twitter-20-body", custom_style=None,
                          extlinks=None, github_user=None, github_repo=None, title=None,
                          book=True, link_resolve=None, nblayout='classic', doc_version=None,
-                         branch='master'):
+                         branch='master', callback_begin=None):
     """
     Defines variables for :epkg:`Sphinx`.
 
@@ -58,6 +58,7 @@ def set_sphinx_variables(fileconf, module_name, author, year, theme, theme_path,
                                         the notebook gallery
     @param      doc_version             if not None, overwrites the current version
     @param      branch                  default branch (`'master'` by default)
+    @param      callback_begin          function to call when the documentation is generated
 
     If the parameter *custom_style* is not None, it will call ``app.add_css_file(custom_style)``
     in the setup.
@@ -486,7 +487,6 @@ def set_sphinx_variables(fileconf, module_name, author, year, theme, theme_path,
         pygments_style = 'monokai'
     elif html_theme == "pydata_sphinx_theme":  # pragma: no cover
         import pydata_sphinx_theme  # pylint: disable=E0401
-        pydata_sphinx_theme
         html_theme_options = {
             "github_user": github_user,
             "github_repo": github_repo,
@@ -623,6 +623,8 @@ def modify_commit_function(nbch, date, author, comment):
     def this_setup(app):  # pragma: no cover
         if custom_style is not None:
             app.add_css_file(custom_style)
+        if callback_begin is not None:
+            callback_begin()
         return custom_setup(app, author)
 
     ext_locals["setup"] = this_setup