In my experience, one difference between a “junior” developer and a “senior” developer is how quickly (if ever) they realize that the architecture needs to be enhanced. Let me give you a simple example…
I was working on a project that stored & manipulated file paths. Sometimes the code worked on a full path like this:
k:\Test\t.txt
Other times it worked on a relative path like this:
Test\t.txt
And sometimes it just worked on a filename:
t.txt
Sometimes the paths were combined or split apart. For instance, “k:\Test\” might be combined with “t.txt” to form “k:\Test\t.txt”.
When I first started working on this project, I stored all the paths as strings. That usually works fine. But this project was different — there was a lot more path manipulation than usual. And I started finding some bugs. In some situations, I had forgotten to include a trailing slash. In other situations, I concatenated two pieces together that both had slashes. I started fixing those bugs one-by-one. But then I realized something: I really needed to enhance the architecture. So I created the following classes:
- FileName
- DirectoryName
- FullFilePath
- RelativeFilePath
- FullDirectoryPath
- RelativeDirectoryPath
Each class had a constructor that accepted a string. Each constructor did three things:
- It verified that the correct type of string was passed in. For instance, the FileName constructor would throw an exception if a full path was passed in.
- It “fixed up” the paths in certain ways. For instance, the RelativeDirectoryPath constructor added a trailing slash if needed. It also converted everything to lower case (to make path comparisons in other parts of the app easier).
- It saved the path so it could be returned from ToString() later.
I also defined some operators and methods to help me convert between the different classes. For instance, I could concatenate a FullDirectoryPath and RelativeFilePath into a FullFilePath using the “+” operator. But there was no such operator to concatenate a FullDirectoryPath and FullFilePath — that made no sense.
Once I started using these classes instead of strings, the bugs quickly disappeared.
I’ve worked with some junior developers that would just continue fixing the bugs one-by-one and never make the leap to creating these classes. But a more senior developer would notice what is happening and realize that the architecture needs to change. The final result? A better architecture that also prevents future bugs. And a useful set of classes that can be re-used in future projects.