Re: Computer Language Shootout

[Preben Randhol <randhol+abuse@pvv.org>]

Robert I. Eachus wrote:
> Matthew Heaney wrote:
> 
>> Do you really mean that End_Of_File and Get_Line use Current_Output?  I
>> thought they used Current_Input.
> 
> Oops! That's what I get for posting after midnight.
> 
>> Aside: I don't ever use End_Of_Line, since the locution
>> 
>>   if Last < Line'Last then
>> 
>> conveys all the information I need wrt whether the entire line has been
>> consumed.  What is End_Of_Line buying me that the idiom above does not?
> 
> Has the actual end of line been consumed?  If the line is the same 
> length as your buffer, the Get_Line can read exactly Last characters but 
> still be positioned at the end of line.  In one case, you will be left 
> at the end of line, and in the other you won't. 

I sometimes use this procedure:

   procedure Get_Whole_Line
      (File : in     File_Type;
       Item :    out String;
       Last :    out Natural)
   is
   begin
      Get_Line (File => File, Item => Item, Last => Last);
      if Last = Item'Last then
         --  The line was longer than allowed, skipping the rest.
         --  Can also raise an exception if necessary.
         Skip_Line (File => File);
      else
         --  Just to remove the extras although it is not really
         --  necessary, can be skipped.
         Fixed.Delete (Source => Item, From => Last + 1, Through => Item'Last);
      end if;

   end Get_Whole_Line;

if I only want to read characters until Item'Last from a file and
consider the rest the line as junk.

> case I think you can read and count a bogus line if the input line is 
> exactly 133 characters long.  The first read will get all 133 
> characters, the second will get no characters and the new line.

But the first is not counted only the second as Last < Item'Last, so I
think it should be correct.

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