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/pushshift.py

@@ -0,0 +1,48 @@
+"""
+Gives you access to older comments possibly not accessible with rexport
+using pushshift
+See https://github.com/seanbreckenridge/pushshift_comment_export
+"""
+
+REQUIRES = [
+    "git+https://github.com/seanbreckenridge/pushshift_comment_export",
+]
+
+from my.core.common import Paths, Stats
+from dataclasses import dataclass
+from my.core.cfg import make_config
+
+from my.config import reddit as uconfig
+
+@dataclass
+class pushshift_config(uconfig.pushshift):
+    '''
+    Uses [[https://github.com/seanbreckenridge/pushshift_comment_export][pushshift]] to get access to old comments
+    '''
+
+    # path[s]/glob to the exported JSON data
+    export_path: Paths
+
+config = make_config(pushshift_config)
+
+from my.core import get_files
+from typing import Sequence, Iterator
+from pathlib import Path
+
+from pushshift_comment_export.dal import read_file, PComment
+
+
+def inputs() -> Sequence[Path]:
+    return get_files(config.export_path)
+
+
+def comments() -> Iterator[PComment]:
+    for f in inputs():
+        yield from read_file(f)
+
+def stats() -> Stats:
+    from my.core import stat
+    return {
+        **stat(comments)
+    }
+