Feature: template in configuration file

examples/template/build_template_example.py

@@ -0,0 +1,8 @@
+import yaml
+
+from pyaml.configuration.factory import Factory
+
+cc = yaml.safe_load(open("templated_config.yaml"))
+
+obj = Factory.build(cc)
+print(obj)

examples/template/templated_config.yaml

@@ -0,0 +1,24 @@
+- class: pyaml.configuration.template.Template
+  template: |
+    class: pyaml.magnet.hcorrector.HCorrector
+    name: %template_parameter%
+    model:
+      class: pyaml.magnet.linear_model.LinearMagnetModel
+      unit: rad
+      hardware_unit: str
+      calibration_factor: 1.0
+      powerconverter: MAGNET/%template_parameter%/B1L
+  string_to_replace: "%template_parameter%"
+  parameter_list:
+    - PKDK_WL_108
+    - PKDK_WL_93
+    - PKDK_WL_79
+    - PKDK_WL_64
+- class: pyaml.magnet.hcorrector.HCorrector
+  name: ANOTHER
+  model:
+    class: pyaml.magnet.linear_model.LinearMagnetModel
+    unit: rad
+    hardware_unit: str
+    calibration_factor: 1.0
+    powerconverter: MAGNET/ANOTHER/B1L

pyaml/configuration/factory.py

@@ -396,7 +396,17 @@ def _build_list(self, items: list[Any], ignore_external: bool = False):
         ignore_external : bool
             If ``True``, ignore unavailable external modules.
         """
-        return [self._build(item, ignore_external) for item in items]
+        list_out = []
+        for item in items:
+            obj = self._build(item, ignore_external)
+            from collections.abc import Iterator
+
+            if isinstance(obj, Iterator):
+                expanded_iterator = [*obj]
+                list_out.extend(expanded_iterator)
+            else:
+                list_out.append(obj)
+        return list_out
 
     def _build_dict(self, data: dict, ignore_external: bool = False):
         """

pyaml/configuration/template.py

@@ -0,0 +1,40 @@
+import json
+
+import yaml
+from pydantic import BaseModel
+
+from ..common.exception import PyAMLConfigException
+from ..configuration.factory import Factory
+from ..validation import StaticValidation, register_schema
+
+
+def load_json_or_yaml(string_to_load: str) -> dict:
+    try:
+        loaded_dict = json.loads(string_to_load)
+        return "json"
+    except json.JSONDecodeError:
+        pass
+
+    try:
+        loaded_dict = yaml.safe_load(string_to_load)
+    except yaml.YAMLError as exc:
+        raise PyAMLConfigException("Template class is not a valid YAML or JSON string.") from exc
+
+    return loaded_dict
+
+
+class TemplateValidationModel(BaseModel):
+    template: str
+    string_to_replace: str
+    parameter_list: list[str]
+
+
+@register_schema
+class Template(StaticValidation):
+    validation_model = TemplateValidationModel
+
+    def __new__(cls, template: str, string_to_replace: str, parameter_list: list[str]):
+        for par in parameter_list:
+            new_string = template.replace(string_to_replace, par)
+            new_dict = load_json_or_yaml(new_string)
+            yield Factory.build(new_dict)

pyaml/validation/validation_models.py

@@ -111,7 +111,12 @@ def __call__(cls, *args: Any, **kwargs: Any):
             raise TypeError(f"{cls.__name__} must define validation_model.")
 
         # Inspect the signature of the class
-        signature = inspect.signature(cls.__init__)
+        if "__init__" in cls.__dict__:
+            signature = inspect.signature(cls.__init__)
+        elif "__new__" in cls.__dict__:
+            signature = inspect.signature(cls.__new__)
+        else:
+            raise Exception
 
         # Map arguments to parameters
         bound = signature.bind(None, *args, **kwargs)