Initial commit

Solutions/5_2/reader.py

@@ -0,0 +1,49 @@
+# reader.py
+
+from abc import ABC, abstractmethod
+import csv
+import logging
+log = logging.getLogger(__name__)
+
+class CSVParser(ABC):
+
+    def parse(self, filename):
+        records = []
+        with open(filename) as f:
+            rows = csv.reader(f)
+            headers = next(rows)
+            for rowno, row in enumerate(rows, start=1):
+                try:
+                    record = self.make_record(headers, row)
+                    records.append(record)
+                except ValueError as e:
+                    log.warning('Row %d: Bad row: %s', rowno, row)
+                    log.debug('Row %d: Reason: %s', rowno, e)
+
+        return records
+
+    @abstractmethod
+    def make_record(self, headers, row):
+        raise NotImplementedError()
+
+class DictCSVParser(CSVParser):
+    def __init__(self, types):
+        self.types = types
+
+    def make_record(self, headers, row):
+        return { name: func(val) for name, func, val in zip(headers, self.types, row) }
+
+class InstanceCSVParser(CSVParser):
+    def __init__(self, cls):
+        self.cls = cls
+
+    def make_record(self, headers, row):
+        return self.cls.from_row(row)
+
+def read_csv_as_dicts(filename, types):
+    parser = DictCSVParser(types)
+    return parser.parse(filename)
+
+def read_csv_as_instances(filename, cls):
+    parser = InstanceCSVParser(cls)
+    return parser.parse(filename)