Unnamed Refactoring
- by Liam McLennan
This post is a message in a bottle. It cast it into the sea in the hope that it will one day return to me, stuffed to the cork with enlightenment. Yesterday I tweeted, what is the name of the pattern where you replace a multi-way conditional with an associative array? I said ‘pattern’ but I meant ‘refactoring’. Anyway, no one replied so I will describe the refactoring here. Programmers tend to think imperatively, which leads to code such as: public int GetPopulation(string country)
{
if (country == "Australia")
{
return 22360793;
} else if (country == "China")
{
return 1324655000;
} else if (country == "Switzerland")
{
return 7782900;
}
else
{
throw new Exception("What ain't no country I ever heard of. They speak English in what?");
}
}
which is horrid. We can write a cleaner version, replacing the multi-way conditional with an associative array, treating the conditional as data:
public int GetPopulation(string country)
{
if (!Populations.ContainsKey(country))
throw new Exception("The population of " + country + " could not be found.");
return Populations[country];
}
private Dictionary<string, int> Populations
{
get
{
return new Dictionary<string, int>
{
{"Australia", 22360793},
{"China", 1324655000},
{"Switzerland", 7782900}
};
}
}
Does this refactoring already have a name? Otherwise, I propose
Replace multi-way conditional with associative array
