Why should I use File.join()?

Question

I wonder why I should use:

puts "In folder #{File.join ENV[HOME], projects}"

Instead of:

puts "In folder #{ENV[HOME]/projects}"

I am aware of that File.join will put the appropriate separator (/ vs \) depending on the OS.

The script is already so tightly tied to what version of ruby you are using, what gems you have installed and so on. My scripts tend not to be like an ORM, (in this case) independent of OS.

I will never run this on Windows (the other dependencies will make the script not to work anyway).

So seems not to be a strong reason for using it, right?

Answer 1

I expect join to handle corner cases gracefully, like when ENV[HOME] is empty for some weird reason.

Answer 2

Any of the following :

File.join("first","second")
File.join("first/","second")
File.join("first","/second")
File.join("first/","/second")

Will return

=> "first/second"

Could it be a good reason for you ?

That's only one example I can think of.

Actually, your goal is not to concatenate 2 strings, your goal is creating a path. This looks like a strong reason to use File.join to me.

Answer 3

Haven't used Ruby, but I expect a Path.join to handle corner cases, like paths ending with or without directory separators. Besides, it expresses intent a bit more clearly than string concatenation, and clarity is IMHO almost always a good idea.

Answer 4

In addition to the other answers your code will be more portable, the correct separator will be used regardless of unix/windows/etc.