my.reddit: refactor into module that supports pushshift/gdpr (#179)

* initial pushshift/rexport merge implementation, using id for merging
* smarter module deprecation warning using regex
* add `RedditBase` from promnesia
* `import_source` helper for gracefully handing mixin data sources

my/reddit/__init__.py

@@ -0,0 +1,41 @@
+"""
+This is here temporarily, for backwards compatability purposes
+It should be removed in the future, and you should replace any imports
+like:
+from my.reddit import ...
+to:
+from my.reddit.all import ...
+since that allows for easier overriding using namespace packages
+https://github.com/karlicoss/HPI/issues/102
+"""
+
+# For now, including this here, since importing the module
+# causes .rexport to be imported, which requires rexport
+REQUIRES = [
+    'git+https://github.com/karlicoss/rexport',
+]
+
+import re
+import traceback
+
+# some hacky traceback to inspect the current stack
+# to see if the user is using the old style of importing
+warn = False
+for f in traceback.extract_stack():
+    line = f.line or '' # just in case it's None, who knows..
+
+    # cover the most common ways of previously interacting with the module
+    if 'import my.reddit ' in (line + ' '):
+        warn = True
+    elif 'from my import reddit' in line:
+        warn = True
+    elif re.match(r"from my\.reddit\simport\s(comments|saved|submissions|upvoted)", line):
+        warn = True
+
+# TODO: add link to instructions to migrate
+if warn:
+    from my.core import warnings as W
+    W.high("DEPRECATED! Instead of my.reddit, import from my.reddit.all instead.")
+
+
+from .rexport import *