"one-to-one correspondence with files in a file system"

Question

I have read in the c# language specification :

Source files typically have a one-to-one correspondence with files in a file system, but this correspondence is not required

What does this exactly mean ?

Interestingly I found a similar definition for other programming languages, where the term `source files` is replaced by `compilation unit`. That term is also mentioned in the C# language definition, but not used here, even though I'd think it would make more sense. — Thorsten Dittmar, Jul 15 '16 at 12:09
My guess the author want to point out that "what you see is not necessarily what is inside file" and vise-versa. Because something you may not see (new line can be `\n` or `\n\r` or `\r\n`, this you don't see), there are questions around where the problem lies in using special character (invisible character) in `string` literals. — Sinatr, Jul 15 '16 at 12:13

score 1 · Accepted Answer · answered Jul 15 '16 at 12:08

As the line before it says:

A source file is an ordered sequence of Unicode characters

That means a "source file" doesn't necessarily have to be a file on the file system. It could be any old stream of bytes that represent characters in UTF-16. It could come from a memory stream, or from a network, or from any old place. But usually it's a file on the file system.

score 0 · Answer 2 · answered Jul 15 '16 at 12:10

I think it literally means that each source file is represented by a single file on the system.

For example, say I have some source code:

Using System;

namespace Test 
{
    public class Program 
    {
        private static void Main (string[] args)
        {
            Console.WriteLine("Hello World!");
        }
    }
}

This can be saved to the file system as Program.cs. We now have some source code which is being represented by a single file on the system.

but this correspondence is not required

Suggests that a source file does not always exist on the system. For example, the source could exist as a "sequence of Unicode characters" instead, which could be stored somewhere in memory.

score 0 · Answer 3 · answered Jul 15 '16 at 12:20

With visual studio, you can "link" a source file within a project. If you place a source file in a project, and link the same source file in a different project (i.e. share the same source code in 2 different projects), you end having 2 sources files linked to a single file.

I usually use this feature in solutions having more than one project: the shared source code is something like this:

[assembly: AssemblyVersion("1.2.3.0")]
[assembly: AssemblyFileVersion("1.2.3.0")]

So when complied, every assembly in my solution have the same version number.

"one-to-one correspondence with files in a file system"

3 Answers3