Paul Pogonyshev created IO-767:
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Summary: FileUtils will become unextendable in future according to
@deprecated comment
Key: IO-767
URL: https://issues.apache.org/jira/browse/IO-767
Project: Commons IO
Issue Type: Wish
Components: Utilities
Affects Versions: 2.11.0
Reporter: Paul Pogonyshev
Source code of FileUtils currently has this in the doccomment before the
constructor: "@deprecated Will be private in 3.0.". This will make FileUtils
unextendable, breaking existing code (e.g. that of our application).
Our usecase: we extend several *Utils classes from Apache Commons libraries to
add our own utility methods, yet still avoid caring if they are "from a
standard library" or our extension. E.g. we can use code like 'import
our.application.FileUtils;' and then 'FileUtils.copyDirectory(...)' (using
Apache-provided method) and 'FileUtils.doSomeFunnyStuff(...)' (using our
internal utility function). Thus we don't clutter 'import' block and avoid
either 1) specifying fully-qualified class name if we had to use two different
'FileUtils' classes; or 2) renaming our class into something ugly like
'OurAppFileUtils'.
If Apache Commons makes their utility classes unextendable, we will no longer
be able to do this. This is the disadvantage for us and anyone else using
similar class layout. I don't see any advantages in making utility classes
unextendable other than having compiler bark at 'new FileUtils()' code some
newcomers would try once in lifetime.
Proposal: make utility classes abstract instead, so that they can be extended,
but not instantiated. If you absolutely want to prohibit instantiation even of
subclasses (also anonymous), add a protected constructor like this:
{{ public FileUtils() {}}
{{ throw new UnsupportedOperationException("FileUtils may not be
instantiated");}}
{{ }}}
Yes, this would at runtime instead of at compilation time, but I'd say that's
worth it for something that should practically never be atempted anyway.
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