Metadata-Version: 1.0
Name: prettysettings
Version: 1.2
Summary: This package provides a minimal class for pretty settings management.
Home-page: https://github.com/iottly/prettysettings
Author: Stefano Terna
Author-email: stefano.terna@tomorrowdata.io
License: Apache License, Version 2.0
Description: # License
        
        Copyright 2015 Stefano Terna
        
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
        You may obtain a copy of the License at
        
            http://www.apache.org/licenses/LICENSE-2.0
        
        Unless required by applicable law or agreed to in writing, software
        distributed under the License is distributed on an "AS IS" BASIS,
        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        See the License for the specific language governing permissions and
        limitations under the License.
        
        # prettysettings
        prettysettings is a minimal library which allows to save and retrieve configuraton settings from a json file and from env variables.
        
        ## Override:
        Override order is:
        - first read from defaults
        - then override from file
        - last override from env variables
        
        ## Keys:
        - defaults dict is used as a reference to load keys from file and from env variables
        - if a key is found in the file (or env vars) which is not present in the defaults it is discarded
        
        ## Types:
        - defaults dict is used to enforce type when loading from file or env variables
        - this ensures that env variables, which must be strings, are parsed to the type used in the default dict
        - parsed types are: `bool`, `int`, `float`, `str`
        - any type `T` for which a string representation exists, so that `T(string)` is the expected object is supported
        - hence if `defaults = {'a': 1}` while the file contains `{'a': '2'}`, the result will be `settings.a == 2` (`int`)
        - whereas if `defaults = {'a': 1}` while the file contains `{'a': 'string'}`, the Settings' constructor will raise an exception
        
        ## Computed settings Hooks
        After reading items from defaults, file, env, the consrtuctor can call hoooks to add custom computed items to the settings object.
        - This can be handy to produce new items which are mere functions of the stored ones.
        - Or it can be useful to add to the settings object complex configuration items (i.e. not serializable to strings).
        - Computed settings are not persisted when updating the settings object.
        
        # Usage
        ## basic usage, just defaults: 
        ```python
        from prettysettings import Settings
        settings = Settings(defaults = {'option1': 1, 'option2': 'myoption'})
        print(settings.option1) # output 1
        print(settings.option2) # output 'myoption'
        ```
        ## load and update from and to file
        
        Say you have `settings.json` containing:
        ```json
        {
            "option1": 2,
            "option2": "my_new_option"
        }
        ```
        then:
        ```python
        from prettysettings import Settings
        settings = Settings(defaults = {'option1': 1, 'option2': 'myoption'}, filename='./settings.json')
        print(settings.option1) # output 2
        print(settings.option2) # output 'my_new_option'
        
        # whereas
        settings = Settings(defaults = {'option1': 1, 'option2': 3}, filename='./settings.json')
        # raises an exception for type incompatibility among option2 in defaults and in file.
        
        ```
        
        About filename:
        - if filename does not exists it is skipped and Settings object is created with defaults
        - this allows to create settings from defaults > updating them > persisting them to file even if it didn't exist at creation time
        
        Say `settings.json` does not exists:
        ```python
        from prettysettings import Settings
        settings = Settings(defaults = {'option1': 1, 'option2': 'myoption'}, filename='./settings.json')
        
        settings.update( {'option2': 'my_new_option'}, persist=True)
        
        ```
        will produce `settings.json` containing:
        ```json
        {
            "option1": 1,
            "option2": "my_new_option"
        }
        ```
        
        ## Computed settings Hooks
        
        ```python
        from prettysettings import Settings
        
        cshooks = {
            'computedoption': lambda settings: 'hey this is computed with {}!!'.format(settings.option2)
        }
        
        settings = Settings(defaults= {'option1': 1, 'option2': 'myoption'}, computed_settings_hooks=cshooks)
        print(settings.option1)          # output 1
        print(settings.option2)          # output 'myoption'
        print(settings.computedoption)   # output 'hey this is computed with myoption!!'
        ```
        
Keywords: prettysettings settings json environment variables
Platform: UNKNOWN
