[fpc-pascal] accessing files from a function

[Anton Shepelev]

Rainer Stratmann:

> Alternatively  you  can make a class or an object with the
> text variable in it.

But if you need to work with only one file, you can get  rid
of  a  global variable in the main module by just extracting
the relevant functions and the file handle into  a  separate
unit:

---------- myfile.pas -------------------------------------
Unit MyFile;
Interface
   Procedure OpenFile(fullname: ShortString);
   Function  ReadNextLine(): ShortString;
   Procedure CloseFile();
   Function  IsFileRead(): Boolean;

Implementation
   var
      TheFile: TEXT;

   Procedure OpenFile(fullname: ShortString);
   begin
      Assign(TheFile, fullname);
      Reset(TheFile);
   end;

   Function ReadNextLine(): ShortString;
   var
      line: ShortString;
   begin
      ReadLn(TheFile, line);
      ReadNextLine := line;
   end;

   Procedure CloseFile();
   begin
      Close(TheFile);
   end;

   Function IsFileRead(): Boolean;
   begin
      IsFileRead := Eof(TheFile);
   end;
end.
----------- filetest.pas ---------------------------------
Program ftest;
uses MyFile;
begin
   OpenFile('test.txt');
   While not IsFileRead() do
      WriteLn(ReadNextLine());
   CloseFile();
end.
----------------------------------------------------------

Anton