Parse callable Tag-Attributes

CHANGES.rst

@@ -5,6 +5,9 @@ History
 2.3.2 (unreleased)
 ------------------
 
+- Parse value if they are callable, for HTML5 Data-Attributes
+  [2silver, 2019-06-12]
+
 - Use ``logger.warning`` instead of deprecated ``logger.warn``.
   [rnix]
 

src/yafowil/utils.py

@@ -279,6 +279,18 @@ def as_data_attrs(data):
             continue
         if val is UNSET:
             continue
+
+        # this probably could be done much better!
+        # 2silver, 2019-06-11
+        if callable(val):
+            try:
+                val = val()
+            except TypeError:
+                logging.warning(
+                    'converting data-attribute for "{}" failed'.format(key)
+                )
+                val = str(val)
+
         # convert value to JSON dump if no string.
         if not isinstance(val, STR_TYPE):
             # also remove leading and trailing double quotes,