AutoArchive._infrastructure.storage

Implementation of storage Storage.

Implements application’s persistent storage interface IStorage. The implementation is provided by FileStorage class. It should be constructed by some infrastructure component and distributed to other components. Individual components should not instantiate it directly.

Modules

_file_storage

FileStorage class.

class AutoArchive._infrastructure.storage._file_storage.FileStorage(configuration)[source]

Bases: object

Application’s persistent storage.

Provides access to application’s persistent storage. Any arbitrary variables can be saved to it. Data are stored in text files.

This storage implementation utilizes local filesystem, specifically a subdirectory of user configuration directory named storage. Data are stored in text files. The directory is automatically created if it does not exists. Storage content is read upon construction and cached into memory. This class does not provide any means to re-read the storage content from disk.

Note

This class can be instantiated only once.

Parameters:configuration (IConfiguration) – Application configuration.
createStoragePortion(section=None, realm=None)[source]

Returns IStoragePortion instance set to section and realm.

Note

If section or realm does not exists the implementation should not create either of them right away but rather on first value save.

Parameters:
  • section (str) – Name of a section within a realm.
  • realm (str) – Name of a separate storage entity (typically represented by a file).
Returns:

IStoragePortion instance

Return type:

IStoragePortion

getRealms()[source]

Returns all realms that exists in the storage.

Returns:Iterable of realm names.
Return type:Iterable<str>
getValue(variable, section=None, realm=None)[source]

Returns a cached value from the persistent storage.

Parameters:
  • variable (str) – The name of the variable which value shall be read.
  • section (str) – Name of a section within a realm.
  • realm (str) – Name of a separate storage entity (typically represented by a file).
Returns:

Value of the passed variable.

Return type:

str

Raises KeyError:
 

If variable, section or realm does not exists.

hasVariable(variable, section=None, realm=None)[source]

Returns True if the storage contains variable.

Parameters:
  • variable (str) – Name of the variable which presence shall be determined.
  • section (str) – Name of a section within a realm.
  • realm (str) – Name of a separate storage entity (typically represented by a file).
Returns:

True if variable is present in the storage.

Return type:

bool

removeRealm(realm)[source]

Deletes the realm including all information that contains from the persistent storage.

Parameters:

realm (str) – Name of a separate storage entity (typically represented by a file).

Raises:
  • KeyError – If realm does not exists.
  • OSError – If an error occurred during the operation of removing data from a physical storage.
saveValue(variable, value, section=None, realm=None)[source]

Saves a value to the persistent storage.

A value passed as value parameter will be saved to the persistent storage under the name passed as variable argument.

Note

A string representation of the value is saved (str(value)).

Parameters:
  • variable (str) – The name under which the value will be saved.
  • value (object) – The value that shall be saved.
  • section (str) – Name of a section within a realm.
  • realm (str) – Name of a separate storage entity (typically represented by a file).
tryRemoveVariable(variable, section=None, realm=None)[source]

Removes variable from the persistent storage.

If variable existed to be removed, returns True; otherwise return False.

Parameters:
  • variable (str) – The name of the variable which value shall be removed.
  • section (str) – Name of a section within a realm.
  • realm (str) – Name of a separate storage entity (typically represented by a file).
Returns:

True if variable existed; False otherwise.

Return type:

bool

Raises KeyError:
 

If section or realm does not exists.

_storage_portion

_StoragePortion class.

class AutoArchive._infrastructure.storage._storage_portion._StoragePortion(storage, section, realm)[source]

Bases: object

Provides access to a part of the persistent storage.

Portion of a storage (which can be any FileStorage-like class) that can be accessed is defined by realm and section. While the section can be changed dynamically, realm can not be changed for entire lifetime of the _StoragePortion-type object.

See also: FileStorage.

Parameters:
  • storage (FileStorage) – Storage which portion shall this instance provide access to.
  • section (str) – Section that shall be accessed by default.
  • realm (str) – Realm that this portion shall provide access to.
getValue(variable, section=None)[source]

Returns a cached value from the persistent storage.

Parameters:
  • variable (str) – The name of the variable which value shall be read.
  • section (str) – Name of a section within realm.
Returns:

Value of the passed variable.

Return type:

str

Raises KeyError:
 

If variable or section does not exists.

hasVariable(variable, section=None)[source]

Returns true if the storage contains variable.

Parameters:
  • variable (str) – Name of the variable which presence shall be determined.
  • section (str) – Name of a section within a realm.
Returns:

true if variable is present in the storage.

Return type:

bool

saveValue(variable, value, section=None)[source]

Saves a value to the persistent storage.

A value passed as value parameter will be saved to a persistent storage under the name passed as variable argument.

Note

A string representation of the value is saved (str(value)).

Parameters:
  • variable (str) – The name under which the value will be saved.
  • value (object) – The value that shall be saved.
  • section (str) – Name of a section within realm.
tryRemoveVariable(variable, section=None)[source]

Removes variable from the persistent storage.

If variable existed to be removed, returns True; otherwise return False.

Parameters:
  • variable (str) – The name of the variable which value shall be removed.
  • section (str) – Name of a section within realm.
Returns:

True if variable existed; False otherwise.

Return type:

bool

Raises KeyError:
 

If section does not exists.

realm

Gets the realm in which this IStoragePortion instance operates.

Return type:str
section

Gets or sets the section in which this IStoragePortion instance operates by default.

Return type:str