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LSSTDataManagementBasePackage
Functions
lsst.utils.doImport Namespace Reference

Functions

def doImport (importable)
 

Function Documentation

◆ doImport()

def lsst.utils.doImport.doImport (   importable)
Import a python object given an importable string and return it.

Parameters
----------
importable : `str`
    String containing dot-separated path of a Python class, module,
    or member function.

Returns
-------
type : `type`
    Type object. Either a module or class or a function.

Raises
------
TypeError
    ``importable`` is not a `str`.
ModuleNotFoundError
    No module in the supplied import string could be found.
ImportError
    ``importable`` is found but can not be imported or the requested
    item could not be retrieved from the imported module.

Definition at line 28 of file doImport.py.

28 def doImport(importable):
29  """Import a python object given an importable string and return it.
30 
31  Parameters
32  ----------
33  importable : `str`
34  String containing dot-separated path of a Python class, module,
35  or member function.
36 
37  Returns
38  -------
39  type : `type`
40  Type object. Either a module or class or a function.
41 
42  Raises
43  ------
44  TypeError
45  ``importable`` is not a `str`.
46  ModuleNotFoundError
47  No module in the supplied import string could be found.
48  ImportError
49  ``importable`` is found but can not be imported or the requested
50  item could not be retrieved from the imported module.
51  """
52  if not isinstance(importable, str):
53  raise TypeError(f"Unhandled type of importable, val: {importable}")
54 
55  def tryImport(module, fromlist):
56  pytype = importlib.import_module(module)
57  # Can have functions inside classes inside modules
58  for f in fromlist:
59  try:
60  pytype = getattr(pytype, f)
61  except AttributeError:
62  raise ImportError(f"Could not get attribute '{f}' from '{module}'")
63  return pytype
64 
65  # Go through the import path attempting to load the module
66  # and retrieve the class or function as an attribute. Shift components
67  # from the module list to the attribute list until something works.
68  moduleComponents = importable.split(".")
69  infileComponents = []
70 
71  while moduleComponents:
72  try:
73  pytype = tryImport(".".join(moduleComponents), infileComponents)
74  if not infileComponents and hasattr(pytype, moduleComponents[-1]):
75  # This module has an attribute with the same name as the
76  # module itself (like doImport.doImport, actually!).
77  # If that attribute was lifted to the package, we should
78  # return the attribute, not the module.
79  try:
80  return tryImport(".".join(moduleComponents[:-1]), moduleComponents[-1:])
81  except ModuleNotFoundError:
82  pass
83  return pytype
84  except ModuleNotFoundError:
85  # Move element from module to file and try again
86  infileComponents.insert(0, moduleComponents.pop())
87 
88  raise ModuleNotFoundError(f"Unable to import {importable}")
89 
def doImport(importable)
Definition: doImport.py:28