template: render() takes a single mapping argument.

This lets it receive other mapping types like ChainMap.

CODE.rst

@@ -61,8 +61,8 @@ Templates receive entry data dicts and format them into final output entries.
 ``__init__(template_str)``
   Initializes the template from a single string, as read from the user's configuration.
 
-``render(payee, amount, currency, date=None, **template_vars)``
-  Returns a string with the output entry, using the given entry data.  This is expected to be called as ``render(**entry_data)``; the arguments take the same types as entry data dicts.
+``render(entry_data)``
+  Returns a string with the output entry, using the given entry data.
 
 Loading importers and hooks
 ---------------------------

import2ledger/template.py

@@ -247,19 +247,23 @@ class Template:
         else:
             self.splitter.set_metadata(str_flat)
 
-    def render(self, payee, amount, currency, date=None, **template_vars):
-        if date is None:
+    def render(self, template_vars):
+        # template_vars must have these keys.  Raise a KeyError if not.
+        template_vars['currency']
+        template_vars['payee']
+        try:
+            date = template_vars['date']
+        except KeyError:
             date = datetime.date.today()
-        template_vars.update(
-            date=date.strftime(self.date_fmt),
-            payee=payee,
-            amount=strparse.currency_decimal(amount),
-            currency=currency,
-        )
+        render_vars = {
+            'amount': strparse.currency_decimal(template_vars['amount']),
+            'date': date.strftime(self.date_fmt),
+        }
         for key, value in template_vars.items():
             if key.endswith('_date'):
-                template_vars[key] = value.strftime(self.date_fmt)
-        return ''.join(f(template_vars) for f in self.format_funcs)
+                render_vars[key] = value.strftime(self.date_fmt)
+        all_vars = collections.ChainMap(render_vars, template_vars)
+        return ''.join(f(all_vars) for f in self.format_funcs)
 
     def is_empty(self):
         return not self.format_funcs

tests/test_templates.py

@@ -1,3 +1,4 @@
+import collections
 import configparser
 import datetime
 import decimal
@@ -17,8 +18,20 @@ with pathlib.Path(DATA_DIR, 'templates.ini').open() as conffile:
 def template_from(section_name, *args, **kwargs):
     return template.Template(config[section_name]['template'], *args, **kwargs)
 
+def template_vars(payee, amount, currency='USD', date=DATE, other_vars=None):
+    call_vars = {
+        'amount': decimal.Decimal(amount),
+        'currency': currency,
+        'date': date,
+        'payee': payee,
+    }
+    if other_vars is None:
+        return call_vars
+    else:
+        return collections.ChainMap(call_vars, other_vars)
+
 def assert_easy_render(tmpl, entity, amount, currency, expect_date, expect_amt):
-    rendered = tmpl.render(entity, decimal.Decimal(amount), currency, DATE)
+    rendered = tmpl.render(template_vars(entity, amount, currency))
     lines = [normalize_whitespace(s) for s in rendered.splitlines()]
     assert lines == [
         "",
@@ -42,17 +55,17 @@ def test_currency_formatting():
 
 def test_empty_template():
     tmpl = template.Template("\n \n")
-    assert tmpl.render('BB', decimal.Decimal('8.99'), 'USD', DATE) == ''
+    assert tmpl.render(template_vars('BB', '8.99')) == ''
     assert tmpl.is_empty()
 
 def test_complex_template():
-    template_vars = {
+    render_vars = template_vars('TT', '125.50', other_vars={
         'entity': 'T-T',
         'program': 'Spectrum Defense',
         'txid': 'ABCDEF',
-    }
+    })
     tmpl = template_from('Complex', date_fmt='%Y-%m-%d', signed_currencies=['USD'])
-    rendered = tmpl.render('TT', decimal.Decimal('125.50'), 'USD', DATE, **template_vars)
+    rendered = tmpl.render(render_vars)
     lines = [normalize_whitespace(s) for s in rendered.splitlines()]
     assert lines == [
         "",
@@ -70,7 +83,7 @@ def test_complex_template():
 
 def test_balancing():
     tmpl = template_from('FiftyFifty')
-    rendered = tmpl.render('FF', decimal.Decimal('1.01'), 'USD', DATE)
+    rendered = tmpl.render(template_vars('FF', '1.01'))
     lines = [normalize_whitespace(s) for s in rendered.splitlines()]
     assert lines == [
         "",
@@ -81,9 +94,11 @@ def test_balancing():
     ]
 
 def test_multivalue():
+    render_vars = template_vars('DD', '150.00', other_vars={
+        'tax': decimal.Decimal('12.50'),
+    })
     tmpl = template_from('Multivalue')
-    rendered = tmpl.render('DD', decimal.Decimal('150.00'), 'USD', DATE,
-                           tax=decimal.Decimal('12.50'))
+    rendered = tmpl.render(render_vars)
     lines = [normalize_whitespace(s) for s in rendered.splitlines()]
     assert lines == [
         "",
@@ -96,9 +111,11 @@ def test_multivalue():
     ]
 
 def test_zeroed_account_skipped():
+    render_vars = template_vars('GG', '110.00', other_vars={
+        'tax': decimal.Decimal(0),
+    })
     tmpl = template_from('Multivalue')
-    rendered = tmpl.render('GG', decimal.Decimal('110.00'), 'USD', DATE,
-                           tax=decimal.Decimal(0))
+    rendered = tmpl.render(render_vars)
     lines = [normalize_whitespace(s) for s in rendered.splitlines()]
     assert lines == [
         "",
@@ -109,9 +126,11 @@ def test_zeroed_account_skipped():
     ]
 
 def test_custom_payee_line():
+    render_vars = template_vars('ZZ', '10.00', other_vars={
+        'custom_date': datetime.date(2014, 2, 13),
+    })
     tmpl = template_from('Custom Payee')
-    rendered = tmpl.render('ZZ', decimal.Decimal('10.00'), 'USD', DATE,
-                           custom_date=datetime.date(2014, 2, 13))
+    rendered = tmpl.render(render_vars)
     lines = [normalize_whitespace(s) for s in rendered.splitlines()]
     assert lines == [
         "",
@@ -121,9 +140,11 @@ def test_custom_payee_line():
     ]
 
 def test_line1_not_custom_payee():
+    render_vars = template_vars('VV', '15.00', other_vars={
+        'custom_date': datetime.date(2014, 2, 12),
+    })
     tmpl = template_from('Simplest')
-    rendered = tmpl.render('VV', decimal.Decimal('15.00'), 'USD', DATE,
-                           custom_date=datetime.date(2014, 2, 12))
+    rendered = tmpl.render(render_vars)
     lines = [normalize_whitespace(s) for s in rendered.splitlines()]
     assert lines == [
         "",