feat: Use logger instead of print(), closes #2

CHANGELOG.rst

@@ -1,6 +1,7 @@
 Unreleased
 ----------
 
+* Use Python's logging module instead of ``print()``.
 * Add support for recent Python versions.
 * Drop support for end-of-life Python versions.
 

docs/index.rst

@@ -82,12 +82,15 @@ Each analysis function must accept a ``data`` argument, which is a :class:`dict`
         # Load the data
         with open('example.csv') as f:
             reader = csv.DictReader(f, fieldnames=['name', 'salary'])
-            reader.next()
+            next(reader)
             data['table'] = list(reader)
 
+    def filter_rows(row):
+        return int(row['salary']) < 25000
+
     def select_rows(data):
         # Select relevant rows from the table
-        data['low_income'] = filter(lambda r: int(r['salary']) < 25000, data['table'])
+        data['low_income'] = list(filter(filter_rows, data['table']))
 
     def calculate_average(data):
         # The average of a value in the rows is taken

example.py

@@ -9,13 +9,17 @@ def load_data(data):
     # Load the data
     with open('example.csv') as f:
         reader = csv.DictReader(f, fieldnames=['name', 'salary'])
-        reader.next()
+        next(reader)
         data['table'] = list(reader)
 
 
+def filter_rows(row):
+    return int(row['salary']) < 25000
+
+
 def select_rows(data):
     # Select relevant rows from the table
-    data['low_income'] = filter(lambda r: int(r['salary']) < 20000, data['table'])
+    data['low_income'] = list(filter(filter_rows, data['table']))
 
 
 def calculate_average(data):

proof/analysis.py

@@ -11,11 +11,18 @@
 import bz2
 import hashlib
 import inspect
+import logging
 import pickle
 import os
 from copy import deepcopy
 from glob import glob
 
+logger = logging.getLogger(__name__)
+logger.setLevel(logging.INFO)
+ch = logging.StreamHandler()
+ch.setLevel(logging.INFO)
+logger.addHandler(ch)
+
 
 class Cache:
     """
@@ -172,15 +179,15 @@ def run(self, refresh=False, _parent_cache=None):
         do_not_cache = getattr(self._func, 'never_cache', False)
 
         if refresh is True:
-            print('Refreshing: %s' % self._name)
+            logger.info('Refreshing: %s' % self._name)
         elif do_not_cache:
             refresh = True
 
-            print('Never cached: %s' % self._name)
+            logger.info('Never cached: %s' % self._name)
         elif not self._cache.check():
             refresh = True
 
-            print('Stale cache: %s' % self._name)
+            logger.info('Stale cache: %s' % self._name)
 
         if refresh:
             if _parent_cache:
@@ -193,7 +200,7 @@ def run(self, refresh=False, _parent_cache=None):
             if not do_not_cache:
                 self._cache.set(local_data)
         else:
-            print('Deferring to cache: %s' % self._name)
+            logger.info('Deferring to cache: %s' % self._name)
 
         for analysis in self._child_analyses:
             analysis.run(refresh=refresh, _parent_cache=self._cache)