Refactor resolvers (#4)

* Refactor resolvers
* Update example

README.md

@@ -88,6 +88,9 @@ For example, `${oc.env:USER,me}` would resolve to the environment variable
 USER with a default value "me".
 Similarly, `${oc.select:path}` will resolve to another configuration value.
 
+Additional resolvers are added to read file contents.
+These are the same as type casts: read_text, read_strip, read_bytes.
+
 The select is used to build multiple templates for configurations by providing
 base configurations.
 An argument `--select key=template` is a shortcut for

alphaconf/__init__.py

@@ -1,6 +1,7 @@
 import contextlib
 import contextvars
 import logging
+import re
 import sys
 from contextvars import ContextVar
 from typing import Any, Callable, Dict, Union, cast
@@ -9,7 +10,7 @@
 
 from .application import Application, _log
 from .arg_parser import ArgumentError, ExitApplication
-from .arg_type import convert_to_type
+from .type_resolvers import convert_to_type
 
 __doc__ = """AlphaConf
 
@@ -24,10 +25,15 @@
 
 """
 
+"""A list of functions which given a key indicate whether it's a secret"""
+SECRET_MASKS = [
+    # mask if contains a kind of secret and it's not in a file
+    re.compile(r'.*(key|password|secret)s?(?!_file)(_|$)').match,
+]
+
 #######################################
 # APPLICATION CONTEXT
 
-
 """The application context"""
 application: ContextVar[Application] = ContextVar('application')
 """The current configuration"""

alphaconf/application.py

@@ -1,6 +1,5 @@
 import logging
 import os
-import re
 import sys
 import uuid
 from typing import Any, Dict, Iterable, List, Optional, Tuple, Union, cast
@@ -16,12 +15,6 @@
 
 _log = logging.getLogger(__name__)
 
-"""A list of functions which given a key indicate whether it's a secret"""
-SECRET_MASKS = [
-    # mask if contains a kind of secret and it's not in a file
-    re.compile(r'.*(password|secret|key)(?!_file)(_|$)').match,
-]
-
 
 class Application:
     """An application description
@@ -298,6 +291,8 @@ def yaml_configuration(self, mask_base: bool = True, mask_secrets: bool = True)
 
     @staticmethod
     def __mask_secrets(configuration):
+        from . import SECRET_MASKS
+
         for key in list(configuration):
             if isinstance(key, str) and any(mask(key) for mask in SECRET_MASKS):
                 configuration[key] = '*****'

alphaconf/type_resolvers.py

@@ -0,0 +1,42 @@
+import datetime
+from pathlib import Path
+
+from omegaconf import OmegaConf
+
+__doc__ = """Resolves types when reading values from the configuration.
+
+You can add values to TYPE_CONVERTER which is used in `alphaconf.get()`.
+This way, you can load values from an external source.
+By the way, you could register new resolvers in OmegaConf.
+"""
+
+
+def read_text(value):
+    return Path(value).expanduser().read_text()
+
+
+TYPE_CONVERTER = {
+    datetime.datetime: datetime.datetime.fromisoformat,
+    datetime.date: lambda s: datetime.datetime.strptime(s, '%Y-%m-%d').date(),
+    datetime.time: datetime.time.fromisoformat,
+    Path: lambda s: Path(s).expanduser(),
+    'read_text': read_text,
+    'read_strip': lambda s: read_text(s).strip(),
+    'read_bytes': lambda s: Path(s).expanduser().read_bytes(),
+}
+
+# register resolved from strings
+for _name, _function in TYPE_CONVERTER.items():
+    if isinstance(_name, str):
+        OmegaConf.register_new_resolver(_name, _function)  # type: ignore
+
+
+def convert_to_type(value, type):
+    """Converts a value to the given type.
+
+    :param value: Any value
+    :param type: A class or a callable used to convert the value
+    :return: Result of the callable
+    """
+    type = TYPE_CONVERTER.get(type, type)
+    return type(value)

example-simple.py

@@ -12,8 +12,14 @@
   url: http://default
   user: ${oc.env:USER}
   home: "~"
+show: false
+exception: false
 """,
-    {"server": "Arguments for the demo"},
+    {
+        "server": "Arguments for the demo",
+        "show": "The name of the selection to show",
+        "exception": "If set, raise an exception",
+    },
 )
 
 
@@ -27,6 +33,10 @@ def main():
     # shortcut version to get a configuration value
     print('server.user:', alphaconf.get('server.user'))
     print('server.home', alphaconf.get('server.home', Path))
+    # show configuration
+    value = alphaconf.get('show')
+    if value and (value := alphaconf.get(value)):
+        print(value)
     # log an exception if we have it in the configuration
     if alphaconf.get('exception'):
         try: