py2store.key_mappers.tuples

Tools to map tuple-structured keys. That is, converting from any of the following kinds of keys:

• tuples (or list-like)

• dicts

• formatted/templated strings

• dsv (Delimiter-Separated Values)

py2store.key_mappers.tuples.dsv_of_list(d, sep=',')

Converting a list of strings to a dsv (delimiter-separated values) string.

Note that unlike most key mappers, there is no schema imposing size here. If you wish to impose a size validation, do so externally (we suggest using a decorator for that).

Parameters

• d – A list of component strings

• sep – The delimiter text used to separate a string into a list of component strings

Returns

The delimiter-separated values (dsv) string for the input tuple

>>> dsv_of_list(['a', 'brown', 'fox'], sep=' ')
'a brown fox'
>>> dsv_of_list(('jumps', 'over'), sep='/')  # for filepaths (and see that tuple inputs work too!)
'jumps/over'
>>> dsv_of_list(['Sat', 'Jan', '1', '1983'], sep=',')  # csv: the usual delimiter-separated values format
'Sat,Jan,1,1983'
>>> dsv_of_list(['First', 'Last'], sep=':::')  # a longer delimiter
'First:::Last'
>>> dsv_of_list(['singleton'], sep='@')  # when the list has only one element
'singleton'
>>> dsv_of_list([], sep='@')  # when the list is empty
''

py2store.key_mappers.tuples.list_of_dsv(d, sep=',')

Converting a dsv (delimiter-separated values) string to the list of it’s components.

Parameters

• d – A (delimiter-separated values) string

• sep – The delimiter text used to separate the string into a list of component strings

Returns

A list of component strings corresponding to the input delimiter-separated values (dsv) string

>>> list_of_dsv('a brown fox', sep=' ')
['a', 'brown', 'fox']
>>> tuple(list_of_dsv('jumps/over', sep='/'))  # for filepaths
('jumps', 'over')
>>> list_of_dsv('Sat,Jan,1,1983', sep=',')  # csv: the usual delimiter-separated values format
['Sat', 'Jan', '1', '1983']
>>> list_of_dsv('First:::Last', sep=':::')  # a longer delimiter
['First', 'Last']
>>> list_of_dsv('singleton', sep='@')  # when the list has only one element
['singleton']
>>> list_of_dsv('', sep='@')  # when the string is empty
[]

py2store.key_mappers.tuples.mk_obj_of_str(constructor)

Make a function that transforms a string to an object. The factory making inverses of what mk_str_from_obj makes.

Parameters

constructor – The function (or class) that will be used to make objects from the **kwargs parsed out of the string.

Returns

A function factory.

py2store.key_mappers.tuples.mk_str_of_obj(attrs)

Make a function that transforms objects to strings, using specific attributes of object.

Parameters

attrs – Attributes that should be read off of the object to make the parameters of the string

Returns

A transformation function

>>> from dataclasses import dataclass
>>> @dataclass
... class A:
...     foo: int
...     bar: str
>>> a = A(foo=0, bar='rin')
>>> a
A(foo=0, bar='rin')
>>>
>>> str_from_obj = mk_str_of_obj(['foo', 'bar'])
>>> str_from_obj(a, 'ST{foo}/{bar}/G')
'ST0/rin/G'

py2store.key_mappers.tuples.str_of_tuple(d, str_format)

Convert tuple to str. It’s just str_format.format(*d). Why even write such a function? (1) To have a consistent interface for key conversions (2) We want a KeyValidationError to occur here :param d: tuple if params to str_format :param str_format: Auto fields format string. If you have manual fields, consider auto_field_format_str to convert.

Returns

parametrized string

>>> str_of_tuple(('hello', 'world'), "Well, {} dear {}!")
'Well, hello dear world!'