fix: import error for `parsers`

[ycexiao]

Problem

Running pytest for diffpy.pdfmorph in the main branch.

FAILED tests/test_pdfmorphapp.py::TestApp::test_parser_systemexits - AttributeError: module 'diffpy.utils.parsers' has no attribute 'loaddata'
FAILED tests/test_pdfmorphapp.py::TestApp::test_morphsequence - AttributeError: module 'diffpy.utils.parsers' has no attribute 'loaddata'
FAILED tests/test_pdfmorphio.py::TestApp::test_morph_outputs - AttributeError: module 'diffpy.utils.parsers' has no attribute 'loaddata'
FAILED tests/test_tools.py::TestTools::test_field_sort - AttributeError: module 'diffpy.utils.parsers' has no attribute 'loaddata'

It comes from diffpy.pdfmorph tools.py

import diffpy.utils.parsers as parsers 
# ...
rv = parsers.loaddata.loadData(fname, unpack=True) 

The problem is related to diffpy.utils's sub-package parsers. Old parser is reconstructed as a sub-package and loaddata is a module now.

Proposed solution

A similar structure found in other projects under diffpy.
e.g. for diffpy.pdfmorph 's sub-package morph. The problem is avoided by importing the package's modules in its __init__.py.

from diffpy.pdfmorph.morphs.morph import Morph  # noqa: F401
from diffpy.pdfmorph.morphs.morphchain import MorphChain  # noqa: F401
# ...

Mirroring this method may solve the problem

[bobleesj]

@ycexiao

am a bit confused. If the API of 'loaddata' has been changed in diffpy.utils, why dont we import it using a new path?

[sbillinge]

I am pretty uncomfortable with this. Why are we doing this? Let's just decide what API we want and fix everything to follow the right API? Is there something special/unusual going on here that requires this fix?

[sbillinge]

Also, looking at the original error message, isn't this a problem with pdfmorph? It doesn't appear to be a problem with diffpy.utils at all?

[ycexiao]

It is actually associated with the compatibility between new diffpy.utils.parsers API and other packages depending on it. If this is the API we want, we can use this, and changing the behaviors of all other packages.

[ycexiao]

Adding one extra line to other .py to add the path can also address this problem.

import diffpy.utils.parsers.<module>

[ycexiao]

I am thinking that other packages in diffpy also use this kind structure to organize modules, and they choose to add imports in the __init__.py. Maybe handling this issue in a consistent way is preferred.

[ycexiao]

I am thinking that other packages in diffpy also use this kind structure to organize modules, and they choose to add imports in the __init__.py. Maybe handling this issue in a consistent way is preferred.

In diffpy.pdfmorph.morphs __init__.py

from diffpy.pdfmorph.morphs.morph import Morph  # noqa: F401                                                          
from diffpy.pdfmorph.morphs.morphchain import MorphChain  # noqa: F401

[ycexiao]

It is a simple situation. Import modules automatically when importing the package, or import them manually at each files.

In old cases, functions are written in one module, so import the module will import these functions.
Now the old module have been written as sub-package, so if we want to use these functions(now modules), we need to either import these modules in the packages (which is consistent with old behavior), or import them in an extra line.

Which one is recommended here ?@sbillinge

[sbillinge]

It is a simple situation. Import modules automatically when importing the package, or import them manually at each files.

In old cases, functions are written in one module, so import the module will import these functions. Now the old module have been written as sub-package, so if we want to use these functions(now modules), we need to either import these modules in the packages (which is consistent with old behavior), or import them in an extra line.

Which one is recommended here ?@sbillinge

import them in the files is the usual standard.

[ycexiao]

It is a simple situation. Import modules automatically when importing the package, or import them manually at each files.
In old cases, functions are written in one module, so import the module will import these functions. Now the old module have been written as sub-package, so if we want to use these functions(now modules), we need to either import these modules in the packages (which is consistent with old behavior), or import them in an extra line.
Which one is recommended here ?@sbillinge

import them in the files is the usual standard.

Thank you! I will open a issue in diffpy.pdfmorph then.