Home » Interfaces and Versioning

Interfaces and Versioning

Solutons:


I think you’re overrusing interfaces.

Meyer and Martin told us: “Open for extension but closed for modification!”

and then Cwalina (et al) reiterated:

From Framework Design Guidelines…

In general, classes are the preferred
construct for exposing abstractions.
The main drawback of interfaces is
that they are much less flexible than
classes when it comes to allowing for
evolution of APIs. Once you ship an
interface, the set of its members is
fixed forever. Any additions to the
interface would break existing types
implementing the interface.

A class offers much more flexibility.
You can add members to classes that
have already shipped. As long as the
method is not abstract (i.e., as long
as you provide a default
implementation of the method), any
existing derived classes continue to
function unchanged.

alt text

Ideally, you shouldn’t be changing your interfaces very often (if at all). If you do need to change an interface, you should reconsider its purpose and see if the original name still applies to it.

If you still feel that the interfaces will change, and the interfaces changes are small (adding items) and you have control of the whole code base, then you should just modify the interface and fix all the compilation errors.

If your change is a change in how the interface is to be used, then you need to create a separate interface (most likely with a different name) to support that alternative usage pattern.

Even if you end up creating ISomething, ISomething2 and ISomething3, the consumers of your interfaces will have a hard time figuring out what the differences are between the interfaces. When should they use ISomething2 and when should they use ISomething3? Then you have to go about the process of obsoleting ISomething and ISomething2.

I agree with Garo Yeriazarian, changing interface is a serious decision. Also, if you want to promote usage of new version of interface you should mark old version as obsolete. In .NET you can add ObsoleteAttribute.

Related Solutions

How to generate a random string?

My favorite way to do it is by using /dev/urandom together with tr to delete unwanted characters. For instance, to get only digits and letters: tr -dc A-Za-z0-9 </dev/urandom | head -c 13 ; echo '' Alternatively, to include more characters from the OWASP...

How to copy a file from a remote server to a local machine?

The syntax for scp is: If you are on the computer from which you want to send file to a remote computer: scp /file/to/send username@remote:/where/to/put Here the remote can be a FQDN or an IP address. On the other hand if you are on the computer wanting to...

What is the difference between curl and wget?

The main differences are: wget's major strong side compared to curl is its ability to download recursively. wget is command line only. There's no lib or anything, but curl's features are powered by libcurl. curl supports FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP,...

Using ‘sed’ to find and replace [duplicate]

sed is the stream editor, in that you can use | (pipe) to send standard streams (STDIN and STDOUT specifically) through sed and alter them programmatically on the fly, making it a handy tool in the Unix philosophy tradition; but can edit files directly, too,...

How do I loop through only directories in bash?

You can specify a slash at the end to match only directories: for d in */ ; do echo "$d" done If you want to exclude symlinks, use a test to continue the loop if the current entry is a link. You need to remove the trailing slash from the name in order for -L to...

How to clear journalctl

The self maintenance method is to vacuum the logs by size or time. Retain only the past two days: journalctl --vacuum-time=2d Retain only the past 500 MB: journalctl --vacuum-size=500M man journalctl for more information. You don't typically clear the journal...

How can I run a command which will survive terminal close?

One of the following 2 should work: $ nohup redshift & or $ redshift & $ disown See the following for a bit more information on how this works: man nohup help disown Difference between nohup, disown and & (be sure to read the comments too) If your...

Get exit status of process that’s piped to another

bash and zsh have an array variable that holds the exit status of each element (command) of the last pipeline executed by the shell. If you are using bash, the array is called PIPESTATUS (case matters!) and the array indicies start at zero: $ false | true $...

Execute vs Read bit. How do directory permissions in Linux work?

When applying permissions to directories on Linux, the permission bits have different meanings than on regular files. The read bit (r) allows the affected user to list the files within the directory The write bit (w) allows the affected user to create, rename,...

What are the pros and cons of Vim and Emacs? [closed]

I use both, although if I had to choose one, I know which one I would pick. Still, I'll try to make an objective comparison on a few issues. Available everywhere? If you're a professional system administrator who works with Unix systems, or a power user on...

How do I use pushd and popd commands?

pushd, popd, and dirs are shell builtins which allow you manipulate the directory stack. This can be used to change directories but return to the directory from which you came. For example start up with the following directories: $ pwd /home/saml/somedir $ ls...

How to forward X over SSH to run graphics applications remotely?

X11 forwarding needs to be enabled on both the client side and the server side. On the client side, the -X (capital X) option to ssh enables X11 forwarding, and you can make this the default (for all connections or for a specific connection) with ForwardX11 yes...

What does “LC_ALL=C” do?

LC_ALL is the environment variable that overrides all the other localisation settings (except $LANGUAGE under some circumstances). Different aspects of localisations (like the thousand separator or decimal point character, character set, sorting order, month,...

What is a bind mount?

What is a bind mount? A bind mount is an alternate view of a directory tree. Classically, mounting creates a view of a storage device as a directory tree. A bind mount instead takes an existing directory tree and replicates it under a different point. The...

Turn off buffering in pipe

Another way to skin this cat is to use the stdbuf program, which is part of the GNU Coreutils (FreeBSD also has its own one). stdbuf -i0 -o0 -e0 command This turns off buffering completely for input, output and error. For some applications, line buffering may...

Can less retain colored output?

Use: git diff --color=always | less -r --color=always is there to tell git to output color codes even if the output is a pipe (not a tty). And -r is there to tell less to interpret those color codes and other escape sequences. Use -R for ANSI color codes only....

How do I copy a folder keeping owners and permissions intact?

sudo cp -rp /home/my_home /media/backup/my_home From cp manpage: -p same as --preserve=mode,ownership,timestamps --preserve[=ATTR_LIST] preserve the specified attributes (default: mode,ownership,timestamps), if possible additional attributes: context, links,...

Can I zip an entire folder using gzip?

No. Unlike zip, gzip functions as a compression algorithm only. Because of various reasons some of which hearken back to the era of tape drives, Unix uses a program named tar to archive data, which can then be compressed with a compression program like gzip,...

How do I check package version using apt-get / aptitude?

apt-get You can run a simulation to see what would happen if you upgrade/install a package: apt-get -s install <package> To see all possible upgrades, run a upgrade in verbose mode and (to be safe) with simulation, press n to cancel: apt-get -V -s upgrade...