core: allow legacy modules to be used in 'hpi module install' for backwards compatibility

but show warning

kinda hacky, but hopefully we will simplify it further when we have more such legacy modules

my/core/__main__.py

@@ -339,6 +339,9 @@ def _requires(modules: Sequence[str]) -> Sequence[str]:
     mods = [module_by_name(module) for module in modules]
     res = []
     for mod in mods:
+        if mod.legacy is not None:
+            warning(mod.legacy)
+
         reqs = mod.requires
         if reqs is None:
             error(f"Module {mod.name} has no REQUIRES specification")

my/core/discovery_pure.py

@@ -34,6 +34,7 @@ class HPIModule(NamedTuple):
     doc: Optional[str] = None
     file: Optional[Path] = None
     requires: Requires = None
+    legacy: Optional[str] = None  # contains reason/deprecation warning
 
 
 def ignored(m: str) -> bool:
@@ -75,9 +76,19 @@ def _is_not_module_src(src: Path) -> bool:
 
 
 def _is_not_module_ast(a: ast.Module) -> bool:
+    marker = NOT_HPI_MODULE_VAR
     return any(
-        getattr(node, 'name', None) == NOT_HPI_MODULE_VAR  # direct definition
-        or any(getattr(n, 'name', None) == NOT_HPI_MODULE_VAR for n in getattr(node, 'names', []))  # import from
+        getattr(node, 'name', None) == marker  # direct definition
+        or any(getattr(n, 'name', None) == marker for n in getattr(node, 'names', []))  # import from
+        for node in a.body
+    )
+
+
+def _is_legacy_module(a: ast.Module) -> bool:
+    marker = 'handle_legacy_import'
+    return any(
+        getattr(node, 'name', None) == marker  # direct definition
+        or any(getattr(n, 'name', None) == marker for n in getattr(node, 'names', []))  # import from
         for node in a.body
     )
 
@@ -156,7 +167,11 @@ def _modules_under_root(my_root: Path) -> Iterable[HPIModule]:
         if ignored(m):
             continue
         a: ast.Module = ast.parse(f.read_text())
-        if _is_not_module_ast(a):
+
+        # legacy modules are 'forced' to be modules so 'hpi module install' still works for older modules
+        # a bit messy, will think how to fix it properly later
+        legacy_module = _is_legacy_module(a)
+        if _is_not_module_ast(a) and not legacy_module:
             continue
         doc = ast.get_docstring(a, clean=False)
 
@@ -166,12 +181,15 @@ def _modules_under_root(my_root: Path) -> Iterable[HPIModule]:
         except Exception as e:
             logging.exception(e)
 
+        legacy = f'{m} is DEPRECATED. Please refer to the module documentation.' if legacy_module else None
+
         yield HPIModule(
             name=m,
             skip_reason=None,
             doc=doc,
             file=f.relative_to(my_root.parent),
             requires=requires,
+            legacy=legacy,
         )
 
 
@@ -209,6 +227,12 @@ def test_requires() -> None:
     assert len(r) == 2  # fragile, but ok for now
 
 
+def test_legacy_modules() -> None:
+    # shouldn't crash
+    module_by_name('my.reddit')
+    module_by_name('my.fbmessenger')
+
+
 def test_pure() -> None:
     """
     We want to keep this module clean of other HPI imports