feat(signature): the change_signature operation (#1533, 4/9)

codebase_rag/constants/ast_python.py

@@ -83,6 +83,10 @@
 # The first parameter of a method that names the instance or class; a
 # signature change keeps it in place and never remaps it.
 PY_RECEIVER_NAMES = frozenset({"self", "cls"})
+# A method reached through the class rather than an instance passes its
+# receiver explicitly: `type(obj).f(obj, a)`, `obj.__class__.f(obj, a)`.
+PY_TYPE_BUILTIN = "type"
+PY_CLASS_ATTRIBUTE = "__class__"
 TS_PY_SUBSCRIPT = "subscript"
 # The `subscript` node's index field (`os.environ["K"]` -> the `"K"` string).
 TS_PY_FIELD_SUBSCRIPT = "subscript"

codebase_rag/constants/cli.py

@@ -993,6 +993,10 @@ class DiffMarker:
     "it to self or cls first"
 )
 SIGNATURE_STAGE_FAILED = "Cannot stage the signature change: {error}"
+SIGNATURE_SOURCE_CHANGED = (
+    "Cannot stage the signature change: {files} changed on disk after the "
+    "change was planned; retry once the tree is settled"
+)
 SIGNATURE_BAD_PARAM = (
     "Not a parameter: `{text}` (expected `name`, `name: type`, `name = default` "
     "or `name: type = default`)"
@@ -1001,6 +1005,9 @@ class DiffMarker:
 SIGNATURE_REQUIRED_AFTER_DEFAULT = (
     "Parameter {name} has no default but comes after a defaulted parameter"
 )
+SIGNATURE_INVALID_HEADER = (
+    "The new parameter list of {qn} is not valid Python ({error}): `{text}`"
+)
 SIGNATURE_BODY_REBINDS = (
     "Cannot rename parameter {old} of {qn} to {new}: `{old}` is used inside a "
     "nested scope, or re-bound by a global, nonlocal or import statement, in "
@@ -1019,6 +1026,10 @@ class DiffMarker:
     "Cannot rename parameter {old} of {qn} to {new}: `{new}` is already used "
     "in its body"
 )
+SIGNATURE_NEW_NAME_TAKEN = (
+    "Cannot add parameter {name} to {qn}: `{name}` is already used in its "
+    "body, which would start reading the parameter instead"
+)
 SIGNATURE_HIERARCHY_MISMATCH = (
     "Cannot change the signature of {qn}: its override {member} declares "
     "({theirs}) where {qn} declares ({ours}); make the hierarchy agree first"
@@ -1057,6 +1068,14 @@ class DiffMarker:
 )
 SIGNATURE_SITE_NO_VALUE = "no value for `{name}`; map it or give it a default"
 SIGNATURE_SITE_OVERLAPS = "its arguments overlap another edit of this change"
+SIGNATURE_SITE_DROPS_EFFECT = (
+    "passes `{text}` for a dropped parameter, and leaving it out would skip "
+    "the code it runs"
+)
+SIGNATURE_SITE_EXPLICIT_RECEIVER = (
+    "reaches the method through its class and passes the receiver as an "
+    "argument (`{text}`); rewrite it by hand"
+)
 SIGNATURE_PLANNED = "{count} site(s) would be rewritten, {skipped} left unmapped"
 SIGNATURE_PARSE_FAILED = "Signature change rolled back: {files} would no longer parse"
 SIGNATURE_CONTRACT_FAILED = (