Merge pull request #19 from matthewrmshin/feature/include-variables-o…

…bject

include (local scope) variable with non-str value

docs/data-process.rst

@@ -304,8 +304,8 @@ string value. If you want to leave the original syntax unchanged for unbound
 variables, set the placeholder VALUE to ``YP_ORIGINAL``.
 
 
-String Value Variable Substitution Include Scope
-------------------------------------------------
+Variable Substitution Include Scope
+-----------------------------------
 
 It is possible to define or override the values of the variables for
 substitution in include files. The scope of the change will be local to the
@@ -378,6 +378,44 @@ Running :program:`yp-data main.yaml <yp-data>` will give:
      car:
        type: Porsche
 
+It is possible to pass variables of any type via the include scope, and
+reference them in a substitution. However, only variables of string type can be
+used in substitution that involves a string concatenation.
+
+Consider:
+
+.. code-block:: yaml
+
+   hello:
+   - INCLUDE: greet.yaml
+     VARIABLES:
+       HELLO: greet
+       TARGETS:
+         - Humans
+         - Martians
+
+
+You can reference ``TARGETS`` in ``greet.yaml`` on its own but not in a string
+substitution.
+
+For example, this causes a ``ValueError``:
+
+.. code-block:: yaml
+
+   # greet.yaml
+   say:
+     - ${HELLO} ${TARGETS}  # Bad, cannot concatenate a list to a string
+     # ...
+
+But this is fine:
+
+.. code-block:: yaml
+
+   # greet.yaml
+   say:
+     - hello: ${HELLO}
+       targets: ${TARGETS}  # Good, value used on its own
+     # ...
 
 String Value Date-Time Substitution
 -----------------------------------

src/yamlprocessor/dataprocess.py

@@ -244,7 +244,7 @@ class DataProcessor:
             },
             VARIABLES_KEY: {
                 'patternProperties': {
-                    r'^[A-z_]\w*$': {'type': 'string'},
+                    r'^[A-z_]\w*$': {'description': 'any valid variable name'},
                 },
                 'additionalProperties': False,
                 'type': 'object',
@@ -563,7 +563,7 @@ def process_variable(
                 else:
                     substitute = groups['symbol']
                 if substitute != groups['symbol'] and groups['cast']:
-                    if groups['head'] or tail != item:
+                    if groups['head'] or groups['tail'] or tail != item:
                         raise ValueError(
                             f'{item}: bad substitution expression')
                     try:
@@ -588,6 +588,9 @@ def process_variable(
                             f'{item}: bad substitution value: {substitute}')
                     ret = substitute
                     tail = ''
+                elif not any(groups[k] for k in ('head', 'escape', 'tail')):
+                    ret = substitute
+                    tail = ''
                 else:
                     ret += (
                         groups['head']

src/yamlprocessor/tests/test_dataprocess.py

@@ -511,6 +511,48 @@ def test_main_14(tmp_path, yaml):
     }
 
 
+def test_main_15(tmp_path, yaml):
+    """Test main, include file with variables as anchor."""
+    yaml_0 = """
+hello: &worlds
+  earth: sapiens
+  mars: martians
+greet:
+  INCLUDE: in_1.yaml
+  VARIABLES:
+    WORLDS: *worlds
+"""
+    yaml_1 = """
+known_worlds: $WORLDS
+other_worlds:
+  pandora: Na'vi people
+  endor: ewoks
+"""
+    infilename = tmp_path / 'in_0.yaml'
+    with infilename.open('w') as infile:
+        infile.write(yaml_0)
+    with (tmp_path / 'in_1.yaml').open('w') as infile:
+        infile.write(yaml_1)
+    outfilename = tmp_path / 'out.yaml'
+    main([str(infilename), str(outfilename)])
+    assert yaml.load(outfilename.open()) == {
+        'hello': {
+            'earth': 'sapiens',
+            'mars': 'martians',
+        },
+        'greet': {
+            'known_worlds': {
+                'earth': 'sapiens',
+                'mars': 'martians',
+            },
+            'other_worlds': {
+                'pandora': 'Na\'vi people',
+                'endor': 'ewoks',
+            },
+        },
+    }
+
+
 def test_main_validate_1(tmp_path, capsys, yaml):
     """Test main, YAML with JSON schema validation."""
     schema = {