Add to_string !eval tag (#9)

Signed-off-by: Joni Pöllänen <[email protected]>

README.adoc

@@ -173,10 +173,13 @@ Examples and tutorials can be found in link:examples[examples] folder.
 |param_configuration.configuration.get_resolved_yaml
 |Resolves the given YAML file and returns a path to it.
 
+|!eval to_string()
+|str()
+|Converts the given value to a string. Handy when using nested evaluations.
+
 |!eval var.<var_name>
 |-
 |Allows using variables which are defined in the beginning of the same file, under ".variables" -key. This key will be removed from the result file.
-
 |===
 
 

param_configuration/tags/eval.py

@@ -39,18 +39,19 @@ def __getattr__(self, item, *args, **kwargs) -> Any:
         return dict.get(item, *args, **kwargs)
 
 
-def names(var: dict[str, Any]) -> dict[str, Any]:
-    """Function proving additional variables for simple eval."""
+def additional_names(var: dict[str, Any]) -> dict[str, Any]:
+    """Function providing additional variables for simple eval."""
     return {"env": os.environ, "m": math, "np": numpy, "var": Dotdict(var)}
 
 
-def functions() -> dict[str, Any]:
+def additional_functions() -> dict[str, Any]:
     """Function providing additional function for simple eval."""
     return {
         "path_to": get_package_share_directory,
         "join": os.path.join,
         "round": round,
         "get_resolved_yaml": get_resolved_yaml,
+        "to_string": str,
     }
 
 
@@ -71,8 +72,10 @@ def constructor(self, tag_value: str, file: str, loader: BaseConstructor) -> Any
         self._vars = self.extract_variables(loader)
 
         default_functions = simpleeval.DEFAULT_FUNCTIONS
-        default_functions.update(functions())
-        res = simpleeval.simple_eval(expr=tag_value, functions=default_functions, names=names(var=self._vars))
+        default_functions.update(additional_functions())
+        res = self.eval_with_compound_types(
+            tag_value, functions=default_functions, names=additional_names(var=self._vars)
+        )
         return res
 
     @staticmethod
@@ -103,6 +106,12 @@ def extract_variables(loader) -> dict:
                             variables |= var
         return variables
 
+    @staticmethod
+    def eval_with_compound_types(tag_value: str, functions: dict[str, Any], names: dict[str, Any]) -> Any:
+        """Evaluates the tag value with compound types."""
+        obj = simpleeval.EvalWithCompoundTypes(functions=functions, names=names)
+        return obj.eval(tag_value)
+
 
 # Add the constructor.
 Configuration().add_config_constructor(const=EvalConfigConstructor)

test/test_configuration.py

@@ -78,6 +78,38 @@ def test_eval_tag_from_string(yaml_string: str) -> None:
         assert data_str == expected_str
 
 
+def test_eval_round() -> None:
+    """Test the !eval directive with the round function."""
+    yaml_string = """
+    round: !eval round(3.141592653589793, 2)
+    """
+    expected_string = "round: 3.14"
+
+    configuration = Configuration()
+    data = configuration.load(yaml_string)
+    data_str = configuration.dump(data)
+    assert data_str == expected_string
+
+
+def test_eval_to_string() -> None:
+    """Test the !eval directive with the to_string function."""
+    yaml_string = """
+    float_to_string: !eval to_string(3.141592653589793)
+    array_to_string: !eval to_string([[1.0, 1.0], [2.0, 2.0]])
+    """
+    # fmt: off
+    expected_string = (
+        "float_to_string: '3.141592653589793'\n"
+        "array_to_string: '[[1.0, 1.0], [2.0, 2.0]]'"
+    )
+    # fmt: on
+
+    configuration = Configuration()
+    data = configuration.load(yaml_string)
+    data_str = configuration.dump(data)
+    assert data_str == expected_string
+
+
 def test_eval_small_numbers() -> None:
     """Test the loading and dumping !eval directive from a string."""
     configuration = Configuration()