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We become accustomed to seeing system messages such as “3 file(s) deleted.” However, this smacks of laziness. One useful function that can be written in your programming language of predilection is plural(). The plural() function is fed parameters of the number and word to be inflected and returns the word approriately inflected. For example, if we call plural(3,'file') it should return ‘files’. When we call plural(1,'file') it should return ‘file’ in order that we can say “1 file deleted” and, oddly enough, plural(0,'file') should return ‘files’, in order that we can say “0 files deleted.”

Of course, English formation of plurals is not regular, so a good implementation of the plural() function would have to deal with the many exceptions in pluralisation, such as class=>classes, potato=>potatoes, data=>data, calf=calves etc. Even then, when the system message is “3 files were deleted”, we also have to deal with the declension of the verb “to be” so as not to end up spouting nonsense like “1 file(s) were deleted”; to avoid the endless complexities of declining irregular verbs, it seems best to avoid verbs in locations in system messages where number is important, i.e. “3 files deleted” rather than “3 files were deleted”.

So, how do we deal with the apparently overwhelming complexities of English grammar, to put out a simple but gramatically-correct system message when we delete a number of files? The resolution is surprisingly easy, achieved by modifying the form of the function plural() so that it takes three arguments: the number, the singular form of the word and the plural form of the word. Thus plural(3,'platypus','platypuses') will return ‘platypuses’, whereas plural(3,'radius','radii') will return ‘radii’, without the need for a long and complex function. Thus "1 "+plural(1,'file,'files')+plural(1,'was,'were')+" deleted" correctly issues
“1 file was deleted” whereas "3 "+plural(3,'file,'files')+plural(3,'was,'were')+" deleted" correctly issues “3 files were deleted”.

Here is the whole of my Perl plural() function:

#**
#* Returns a string with correct plural treatment.
#*
#* @author Modulus Pty. Ltd. - prh
#* @version 2008 1.0
#* @param $nr the number governing the result
#* @param $sstr the singular string e.g. 'match'
#* @param $pstr the plural string e.g. 'matches'
#* @return $sstr or $pstr
sub lib_plural{
   shift == 1 ? shift: $_[1];
}

Tags: algorithms

This entry was posted on Wednesday, November 12th, 2008 at 16:28 pm and is filed under algorithms. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.