Use f-strings where reasonable

But don't report not using them as linting error.

Author: Cito

.pylintrc

@@ -13,6 +13,7 @@ init-hook = sys.path.insert(0, 'webware')
 disable =
  attribute-defined-outside-init,
  broad-except,
+ consider-using-f-string,
  cyclic-import,
  similarities,
  eval-used,

webware/Admin/ServletCache.py

@@ -34,13 +34,13 @@ def writeContent(self):
             wr('<table>')
             for factory in factories:
                 name = factory.name()
-                wr('<tr><td><a href="#{0}">{0}</a></td></tr>'.format(name))
+                wr(f'<tr><td><a href="#{name}">{name}</a></td></tr>')
             wr('</table>')
         hasField = self.request().hasField
         wr('<form action="ServletCache" method="post">')
         for factory in factories:
             name = factory.name()
-            wr('<a id="{0}"></a><h4>{0}</h4>'.format(name))
+            wr(f'<a id="{name}"></a><h4>{name}</h4>')
             if hasField('flush_' + name):
                 factory.flushCache()
                 wr('<p style="color:green">'

webware/Examples/ListBox.py

@@ -21,24 +21,24 @@ def awake(self, transaction):
             self._vars = session.value('vars')
         else:
             self._vars = dict(
-                items=[], height=10, width=250,
-                newCount=1, formCount=1)
+                items=[], height=10, width=250, newCount=1, formCount=1)
             session.setValue('vars', self._vars)
         self._error = None
 
     def writeContent(self):
         enc, wr = self.htmlEncode, self.writeln
         wr('<div style="text-align:center">')
         if debug:
-            wr('<p>fields = {}</p>'.format(enc(str(self.request().fields()))))
-            wr('<p>vars = {}</p>'.format(enc(str(self._vars))))
+            wr(f'<p>fields = {enc(str(self.request().fields()))}</p>')
+            wr(f'<p>vars = {enc(str(self._vars))}</p>')
         # Intro text is provided by our class' doc string:
         intro = self.__class__.__doc__.strip().split('\n\n')
-        wr('<h2>{}</h2>'.format(intro.pop(0)))
+        wr(f'<h2>{intro.pop(0)}</h2>')
         for s in intro:
-            wr('<p>{}</p>'.format('<br>'.join(
-                s.strip() for s in s.splitlines())))
-        wr('<p style="color:red">{}</p>'.format(self._error or '&nbsp;'))
+            s = '<br>'.join(s.strip() for s in s.splitlines())
+            wr(f'<p>{s}</p>')
+        s = self._error or '&nbsp;'
+        wr(f'<p style="color:red">{s}</p>')
         wr('''
 <form action="ListBox" method="post">
 <input name="formCount" type="hidden" value="{formCount}">
@@ -47,8 +47,8 @@ def writeContent(self):
 '''.format(**self._vars))
         index = 0
         for item in self._vars['items']:
-            wr('<option value="{}">{}</option>'.format(
-                index, enc(item['name'])))
+            name = enc(item['name'])
+            wr(f'<option value="{index}">{name}</option>')
             index += 1
         if not index:
             wr('<option value="" disabled>--- empty ---</option>')
@@ -80,8 +80,8 @@ def widthChange():
 
     def new(self):
         """Add a new item to the list box."""
-        self._vars['items'].append(dict(
-            name='New item {}'.format(self._vars['newCount'])))
+        newCount = self._vars['newCount']
+        self._vars['items'].append(dict(name=f'New item {newCount}'))
         self._vars['newCount'] += 1
         self.writeBody()
 

webware/Examples/View.py

@@ -23,9 +23,8 @@ def writeContent(self):
             filename = req.field('filename')
             if sep in filename:
                 self.write(
-                    '<h3 style="color:red">Error</h3>'
-                    '<p>Cannot request a file'
-                    ' outside of this directory {filename!r}</p>')
+                    '<h3 style="color:red">Error</h3><p>Cannot request a file'
+                    f' outside of this directory {filename!r}</p>')
                 return
             filename = self.request().serverSidePath(filename)
             self.request().fields()['filename'] = filename

webware/MiscUtils/CSVJoiner.py

@@ -17,7 +17,8 @@ def joinCSVFields(fields):
         if not isinstance(field, str):
             raise UnicodeDecodeError('CSV fields should be strings')
         if '"' in field:
-            newField = '"{}"'.format(field.replace('"', '""'))
+            field = field.replace('"', '""')
+            newField = f'"{field}"'
         elif ',' in field or '\n' in field or '\r' in field:
             newField = f'"{field}"'
         else:

webware/MiscUtils/DictForArgs.py

@@ -13,7 +13,7 @@ class DictForArgsError(Exception):
 
 
 def _SyntaxError(s):
-    raise DictForArgsError('Syntax error: %r' % s)
+    raise DictForArgsError(f'Syntax error: {s!r}')
 
 
 _nameRE = re.compile(r'\w+')

webware/MiscUtils/Tests/TestDictForArgs.py

@@ -64,11 +64,9 @@ def _testNegative(self, input_):
         except DictForArgsError:
             pass  # expected
         except Exception as err:
-            self.fail(
-                f'Expecting DictForArgError.\nGot error: {err!r}.\n')
+            self.fail(f'Expecting DictForArgError.\nGot error: {err!r}.\n')
         else:
-            self.fail(
-                f'Expecting DictForArgError.\nGot result: {res!r}.\n')
+            self.fail(f'Expecting DictForArgError.\nGot result: {res!r}.\n')
 
     def testPyDictForArgs(self):
         cases = '''\

webware/MiscUtils/Tests/TestNamedValueAccess.py

@@ -91,10 +91,10 @@ def testBasicAccess(self):
         # pylint: disable=assignment-from-no-return,no-member
         for obj in self.objs:
             value = func(obj, 'foo')
-            self.assertEqual(value, 1, 'value = %r, obj = %r' % (value, obj))
+            self.assertEqual(value, 1, f'value = {value!r}, obj = {obj!r}')
             self.assertRaises(NamedValueAccessError, func, obj, 'bar')
             value = func(obj, 'bar', 2)
-            self.assertEqual(value, 2, 'value = %r, obj = %r' % (value, obj))
+            self.assertEqual(value, 2, f'value = {value!r}, obj = {obj!r}')
 
     def testBasicAccessRepeated(self):
         """Just repeat checkBasicAccess multiple times to check stability."""

webware/WebUtils/Funcs.py

@@ -80,7 +80,7 @@ def htmlForDict(d, addSpace=None, filterValueCallBack=None,
         if isinstance(topHeading, tuple):
             append('<th>{}</th><th>{}</th>'.format(*topHeading))
         else:
-            append('<th colspan="2">{}</th>'.format(topHeading))
+            append(f'<th colspan="2">{topHeading}</th>')
         append('</tr>\n')
     for key in sorted(d):
         value = d[key]

webware/WebUtils/HTTPStatusCodes.py

@@ -62,11 +62,11 @@ def htmlTableOfHTTPStatusCodes(
 
 
 if __name__ == '__main__':
-    print('''<html>
+    print(f'''<html>
 <head>
     <title>HTTP Status Codes</title>
 </head>
 <body>
-{}
+{htmlTableOfHTTPStatusCodes()}
 </body>
-</html>'''.format(htmlTableOfHTTPStatusCodes()))
+</html>''')