Why does File.byLine() return char[] and not string

[Meta via Digitalmars-d-learn]

On Sunday, 18 October 2015 at 15:03:22 UTC, Suliman wrote:
> Sorry, but could you explain more simply? I reread all 
> information, bit can't understand about what buffer you are 
> talking.

This is more or less how byLine works, simplified:

struct ByLine
{
     File file;
     char[] line;
     char[] buffer;
     char terminator;

     bool empty() { return line is null; }
     char[] front() { return line; }

     void popFront()
     {
         line = buffer;
         file.readLine(line, terminator); //This overwrites the 
current contents of line
         if (line.length > buffer.length)
         {
             buffer = line;
         }

         if (line.empty) line = null;
     }
}

auto byLine(string fileName, char terminator = '\n')
{
     return ByLine(File(fileName), terminator);
}


> And what is "signal"? How it's working?

It's just an expression that means "to convey information". So 
when ByLine.front returns char[], a mutable array of char, it's 
meant to convey to the programmer that since the return value is 
mutable, it could change and they should make a copy.