Avoid issues with early evaluation of argument defaults

bin/nexrad-archive-afos-ingest

@@ -1,6 +1,7 @@
 #! /usr/bin/env python3
 
 import sys
+import argparse
 
 from nexrad.db   import Database
 from nexrad.afos import AFOSMessageParser
@@ -27,6 +28,9 @@ def each_chunk(fh, sep: str):
             else:
                 yield part.strip()
 
+ap = argparse.ArgumentParser(description='Ingest bulk AFOS text messages')
+ap.add_argument('--poly-only', action='store_true', help='Ingest only AFOS messages with geographic bounding polygons')
+
 db = Database.connect(sys.argv[1])
 db.execute('begin transaction')
 

lib/nexrad/db.py

@@ -1,6 +1,8 @@
 import enum
 import sqlite3
 
+from nexrad.util import default
+
 class DatabaseOrder(enum.Enum):
     DEFAULT = 0
     ASC     = 1
@@ -210,13 +212,15 @@ class Database():
 
         self.db.execute(sql, values)
 
-    def query_sql(self, table, sql, values=list()):
+    def query_sql(self, table, sql, values=None):
         cr = DatabaseTableCursor(table, self.db.cursor())
-        cr.execute(sql, values)
+        cr.execute(sql, default(values, list()))
 
         return cr
 
-    def query(self, table, values=dict(), order_by=list()):
+    def query(self, table, values=None, order_by=None):
+        values    = default(values,   dict())
+        order_by  = default(order_by, list())
         selectors = getattr(table, '__columns_read__', None)
 
         if selectors is None:
@@ -253,10 +257,12 @@ class Database():
 
         return self.query_sql(table, sql, list(values.values()))
 
-    def get(self, table, values: dict=dict()):
-        return self.query(table, values).fetchone()
+    def get(self, table, values: dict=None):
+        return self.query(table, default(values, dict())).fetchone()
+
+    def _call(self, table, fn: str, column: str, values: dict=None) -> int:
+        values = default(values, dict())
 
-    def _call(self, table, fn: str, column: str, values: dict=dict()) -> int:
         sql = f"select {fn}({column}) as ret from {table.__table__}"
 
         if len(values) > 0:
@@ -267,11 +273,11 @@ class Database():
 
         return row[0] if row is not None else None
 
-    def min(self, table, column: str, values: dict=dict()) -> int:
-        return self._call(table, 'min', column, values)
+    def min(self, table, column: str, values: dict=None) -> int:
+        return self._call(table, 'min', column, default(values, dict()))
 
-    def max(self, table, column: str, values: dict=dict()) -> int:
-        return self._call(table, 'max', column, values)
+    def max(self, table, column: str, values: dict=None) -> int:
+        return self._call(table, 'max', column, default(values, dict()))
 
-    def count(self, table, values: dict=dict()) -> int:
-        return self._call(table, 'count', table.__key__, values)
+    def count(self, table, values: dict=None) -> int:
+        return self._call(table, 'count', table.__key__, default(values, dict()))

lib/nexrad/util.py

@@ -0,0 +1,2 @@
+def default(a, b):
+    return b if a is None else a