symforce.python_util module

General python utilities.

remove_if_exists(path)

Delete a file or directory if it exists.

Parameters:

path (Union[str, PathLike]) –

Return type:

None

execute_subprocess(cmd, stdin_data=None, log_stdout=True, log_stdout_to_error_on_error=True, **kwargs)

Execute subprocess and log command as well as stdout/stderr.

Parameters:

• stdin_data (bytes) – Data to pass to stdin

• log_stdout (bool) – Write process stdout to the logger?

• log_stdout_to_error_on_error (bool) – Write output to logger.error if the command fails?

• cmd (Union[str, Sequence[str]]) –

• kwargs (Any) –

Raises:

subprocess.CalledProcessError – If the return code is nonzero

Return type:

str

camelcase_to_snakecase(s)

Convert CamelCase -> snake_case.

Parameters:

s (str) –

Return type:

str

snakecase_to_camelcase(s)

Convert snake_case -> CamelCase

Double underscores are escaped, e.g. one__two becomes One_Two

Parameters:

s (str) –

Return type:

str

camelcase_to_screaming_snakecase(s)

Convert CamelCase -> SCREAMING_SNAKE_CASE

Parameters:

s (str) –

Return type:

str

str_replace_all(s, replacements)

Call str.replace(old, new) for every pair (old, new) in replacements

Parameters:

• s (str) –

• replacements (Dict[str, str]) –

Return type:

str

str_removeprefix(s, prefix)

Backport of str.removeprefix, from Python3.9 https://docs.python.org/3/library/stdtypes.html#str.removeprefix

If the string starts with the prefix string and that prefix is not empty, return string[len(prefix):]. Otherwise, return a copy of the original string.

Parameters:

• s (str) –

• prefix (str) –

Return type:

str

str_removesuffix(s, suffix)

Backport of str.removesuffix, from Python3.9 https://docs.python.org/3/library/stdtypes.html#str.removesuffix

If the string ends with the suffix string and that suffix is not empty, return string[:-len(suffix)]. Otherwise, return a copy of the original string.

Parameters:

• s (str) –

• suffix (str) –

Return type:

str

files_in_dir(dirname, relative=False)

Return a list of files in the given directory.

Parameters:

• dirname (Union[str, PathLike]) –

• relative (bool) –

Return type:

Iterator[str]

id_generator(size=6, chars='ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789')

Generate a random string within a character set - for example “6U1S75”. This is not cryptographically secure.

Parameters:

• size (int) –

• chars (str) –

Return type:

str

getattr_recursive(obj, attrs)

Recursively calls getattr on obj with the attributes in attrs and returns the output. If attr is empty, returns obj.

Example

get_attr_recursive(obj, [“A”, “B”, “C”]) returns the same thing as obj.A.B.C

Parameters:

• obj (object) –

• attrs (Sequence[str]) –

Return type:

Any

exception InvalidKeyError

Bases: ValueError

exception InvalidPythonIdentifierError

Bases: InvalidKeyError

base_and_indices(indexed_array)

Decomposes indexed_array into (base, indices) in the sense that, “arr[1][2]” -> (“arr”, [1, 2]). base is the initial substring of indexed_array that does not contain either “[” or “]”; indices is is the list of integer indices indexing into the array denoted by base.

indices will be the empty list if indexed_array has no indices.

Raises:

• InvalidKeyError if indexed_array is not matched by the regular expression –

• r"[[]]*([[0-9]+])*", i.e., is not a string with no square brackets, –

• followed by 0 or more integers wrapped in square brackets. –

Example

>>> assert ("arr", []) == base_and_indices("arr")
>>> assert ("arr", [1, 2, 3]) == base_and_indices("arr[1][2][3]")
>>> try:
>>>     base_and_indices("arr[1].bad[2]")
>>>     assert False
>>> except ValueError:
>>>     pass
>>> except:
>>>     assert False

Parameters:

indexed_array (str) –

Return type:

Tuple[str, List[int]]

plural(singular, count, plural=None)

Return the singular or plural form of a word based on count

Adds an s to singular by default for the plural form, or uses plural if provided

Parameters:

• singular (str) –

• count (int) –

• plural (Optional[str]) –

Return type:

str

get_func_from_maybe_bound_function(func)

Get the original function, from a function possibly bound by functools.partial

Parameters:

func (Callable) –

Return type:

Callable

get_class_for_method(func)

Get the class from an instance method func

See https://stackoverflow.com/a/25959545

Parameters:

func (Callable) –

Return type:

Type

class AttrDict(**kwargs)

Bases: dict

A simple attr-dict, i.e. a dictinary whose keys are also accessible directly as fields

Based on http://stackoverflow.com/a/14620633/53997

Parameters:

kwargs (Any) –

__init__(**kwargs)

Parameters:

kwargs (Any) –