Das deutsche Python-Forum

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# Meta-Bemerkungen (in deutscher Sprache) entfallen ab dem pre-release.
# Sie dienen bis dahin ausschließlich Kommentaren, welche zum leichteren Verständnis des aktuellen Code-Status dienen

# !access settings via this function only please!
def settings(mode, keywrd, value):
    """
    Requires:
      # hier stehen momentan nur zwei Platzhalter
      environement(...)
      custom_error_handling(...)

    At program start, data_dict is loaded either 
    from default_dict or from a settings-file
    
    Arguments use:

      mode                  keywrd        value
      ----                  ------        -----
      'read_default_data'   None          None
        return: data_dict

      'save_settings_dict'  None          None
        return: data_dict

      'get_keyval'          dict-key      None
        return: value

      'update_keyval'       dict-key      value
        return: value

    Access samples:
      settings('read_default_data', None, None)
      settings('save_settings_dict', None, None)
      settings('get_keyval', key, None)
      settings('update_value', key, value)
    """

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1 < len(args) > 3

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1 < len(args) and len(args) > 3

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1 < len(args) and 3 < len(args)

Code: Alles auswählen

### B I T T E  V O R S I C H T ###
# Es könnte zu Testzwecken eine Testdatei in das
# Arbeitsverzeichnis geschrieben werden!
# Der Dateiname ist jedoch so gewählt, dass ein
# Konflikt zu unser aller Lebzeiten - auch in Summe -
# eher nicht vorkommen kann. :-)

# Meta-Bemerkungen (in deutscher Sprache):
#  Diese entfallen ab dem pre-release
#  Sie dienen bis dahin ausschließlich Kommentaren,
#  welche dem leichteren Verständnis des aktuellen
#  Code-Status während der Entwicklung dienen

# Laufzeitumgebung (Planungsgrundlage):
#   Win10, Python3
#   Umgebungsvariablen wie z. B. Installationsverzeichnis,
#   Zugriffsrechte etc. werden an anderem Ort überprüft

# BS-Unabhängigkeit:
#   Betriebssystem-Unabhängigkeit hat ! Erste Priorität !
#   (Sofern für das aktuelle target-System begründet
#   keine alternativen, proprietären Optionen vorzuziehen sind

import os
import json

# define customError class to intercept possible
# errors during coding of the APP
class customError(Exception):
    pass

# !access settings dictionary via this function only please!
def settings(task, keyword, value):
    u"""
    Read write settings data.
    
    At program start, settings_data is loaded either 
    from DEFAULT_SETTINGS or from data_path (settings-file).
    
    The arguments use is self-explanatory:

      task                  keyword        value
      ----                  ------        -----
      'read_default_data'   None          None
        return: settings_data

      'save_settings_data'  None          None
        return: settings_data

      'get_keyval'          dict-key      None
        return: value

      'update_keyval'       dict-key      value
        return: value

    Access samples:
      settings('read_default_data', None, None)
      settings('save_settings_data', None, None)
      settings('get_keyval', key, None)
      settings('update_keyval', key, value)

      # raise a customError:
      settings('read_default_data', None, 'any item except "None"')
    """

    ERR_MSG_ARG   = 'An arg != None was encountered unexpectedly'
    ERR_MSG_ARGS  = 'The type of at least one of two arguments was detected to be != None'
    ERR_MSG_TYPE  = 'Arg one unexpectedly was not of type string'
    ERR_MSG_TASK  = 'Arg one was not interpretable'

    # Arbeitsverzeichnis und Dateiname ist temporär !!!
    data_path = '.\\dummy_f_dfg_ff__Y_TmP_mydata.json'

    # defaults for settings data
    DEFAULT_SETTINGS = {
      '_del_orphaned':    False,  # if true:  del orphaned versions
      '_demo_only':       False,  # if true:  demo only
      '_hide_versions':   False,  # if true:  hide
      '_symlinks_dirs':   False,  # if false: ignore
      '_symlinks_files':  False,  # if false: ignore
      # 'scan_all_subdirs', # visibility of subdirs for power-user
    }

    # load settings_data
    if not os.path.exists(data_path):
        settings_data = DEFAULT_SETTINGS
    else:
        with open(data_path, 'r') as f:
            settings_data = json.load(f)    

    # get DEFAULT_SETTINGS
    if task == 'read_default_data':
        if keyword != None or value != None:
            raise customError(ERR_MSG_ARGS)
            quit()

        return DEFAULT_SETTINGS

    # save settings to disc
    elif task == 'save_settings_data':
        if keyword != None or value != None:
            raise customError(ERR_MSG_ARGS)
            quit()

        with open(data_path, 'w') as f:
           json.dump(settings_data, f)

        return settings_data

    # get a settings value
    elif task == 'get_keyval':
        # if not type(value) == str:
            # raise customError(ERR_MSG_TYPE)
            # quit()

        return settings_data[keyword]

    # update a dict value and save it
    elif task == 'update_keyval':
        # if not type(value) == str:
            # raise customError(ERR_MSG_TYPE)
            # quit()

        settings_data['keyword'] = value
        with open(data_path, 'w') as f:
           json.dump(settings_data, f)

        return settings_data[keyword]

    else:
        raise customError(ERR_MSG_TASK)
        quit()

print("settings('read_default_data', None, None)")
print(settings('read_default_data', None, None))
print()

print("settings('save_settings_data', None, None)")
settings('save_settings_data', None, None)

settings('get_keyval', '_hide_versions', None)
print("settings('get_keyval', '_hide_versions', None)")

settings('update_keyval', '_hide_versions', True)
print("settings('update_keyval', '_hide_versions', True)")

# raise a customError:
# print("settings('read_default_data', None, 'any item except None'")
# print(settings('read_default_data', None, 'any item except None'))