How do I write good correct package init py files

Question

My package has the following structure   mobilescouter        init   py  1     mapper            init   py   2         lxml                init   py  3             vehiclemapper py             vehiclefeaturemapper py             vehiclefeaturesetmapper py                     basemapper py    vehicle            init   py  4         vehicle py         vehiclefeature py         vehiclefeaturemapper py          I m not sure how the   init   py files should be correctly written  The   init   py  1 looks like     all       mapper    vehicle   import mapper import vehicle   But how should for example   init   py  2 look like  Mine is     all       basemapper    lxml   from basemaper import   import lxml   When should be   all   used

User · Answer

My own   init   py files are empty more often than not   In particular  I never have a from blah import   as part of   init   py -- if  importing the package  means getting all sort of classes  functions etc defined directly as part of the package  then I would lexically copy the contents of blah py into the package s   init   py instead and remove blah py  the multiplication of source files does no good here    If you do insist on supporting the import   idioms  eek   then using   all    with as miniscule a list of names as you can bring yourself to have in it  may help for damage control  In general  namespaces and explicit imports are good things  and I strong suggest reconsidering any approach based on systematically bypassing either or both concepts -

User · Answer

all   is very good - it helps guide import statements without automatically importing modules http   docs python org tutorial modules html importing-from-a-package  using   all   and import   is redundant  only   all   is needed  I think one of the most powerful reasons to use import   in an   init   py to import packages is to be able to refactor a script that has grown into multiple scripts without breaking an existing application  But if you re designing a package from the start  I think it s best to leave   init   py files empty   for example   foo py - contains classes related to foo such as fooFactory  tallFoo  shortFoo   then the app grows and now it s a whole folder  foo        init   py     foofactories py     tallFoos py     shortfoos py     mediumfoos py     santaslittlehelperfoo py     superawsomefoo py     anotherfoo py   then the init script can say    all       foofactories    tallFoos    shortfoos    medumfoos               santaslittlehelperfoo    superawsomefoo    anotherfoo     deprecated to keep older scripts who import this from breaking from foo foofactories import fooFactory from foo tallfoos import tallFoo from foo shortfoos import shortFoo   so that a script written to do the following does not break during the change   from foo import fooFactory  tallFoo  shortFoo

User · Answer

Your   init   py should have a docstring   Although all the functionality is implemented in modules and subpackages  your package docstring is the place to document where to start   For example  consider the python email package   The package documentation is an introduction describing the purpose  background  and how the various components within the package work together   If you automatically generate documentation from docstrings using sphinx or another package  the package docstring is exactly the right place to describe such an introduction   For any other content  see the excellent answers by firecrow and Alex Martelli

[python] How do I write good/correct package init.py files

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[python] How do I write good/correct package init.py files