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| -rw-r--r-- | Doc/tutorial/modules.rst | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/Doc/tutorial/modules.rst b/Doc/tutorial/modules.rst index 42a52e5..6f51357 100644 --- a/Doc/tutorial/modules.rst +++ b/Doc/tutorial/modules.rst @@ -103,6 +103,10 @@ There is even a variant to import all names that a module defines:: This imports all names except those beginning with an underscore (``_``). +Note that in general the practice of importing ``*`` from a module or package is +frowned upon, since it often causes poorly readable code. However, it is okay to +use it to save typing in interactive sessions. + .. note:: For efficiency reasons, each module is only imported once per interpreter @@ -443,14 +447,9 @@ Importing \* From a Package Now what happens when the user writes ``from sound.effects import *``? Ideally, one would hope that this somehow goes out to the filesystem, finds which -submodules are present in the package, and imports them all. Unfortunately, -this operation does not work very well on Windows platforms, where the -filesystem does not always have accurate information about the case of a -filename. On these platforms, there is no guaranteed way to know whether a file -:file:`ECHO.PY` should be imported as a module :mod:`echo`, :mod:`Echo` or -:mod:`ECHO`. (For example, Windows 95 has the annoying practice of showing all -file names with a capitalized first letter.) The DOS 8+3 filename restriction -adds another interesting problem for long module names. +submodules are present in the package, and imports them all. This could take a +long time and importing sub-modules might have unwanted side-effects that should +only happen when the sub-module is explicitly imported. The only solution is for the package author to provide an explicit index of the package. The :keyword:`import` statement uses the following convention: if a package's @@ -485,10 +484,9 @@ current namespace because they are defined in the :mod:`sound.effects` package when the ``from...import`` statement is executed. (This also works when ``__all__`` is defined.) -Note that in general the practice of importing ``*`` from a module or package is -frowned upon, since it often causes poorly readable code. However, it is okay to -use it to save typing in interactive sessions, and certain modules are designed -to export only names that follow certain patterns. +Although certain modules are designed to export only names that follow certain +patterns when you use ``import *``, it is still considered bad practise in +production code. Remember, there is nothing wrong with using ``from Package import specific_submodule``! In fact, this is the recommended notation unless the |