Reduce lines of code in function to read files in Delphi [closed] - delphi

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I'm trying to cut the lines of this code and I do not see how the code I show is the minimum of lines that could achieve:
function read_file(FileName: String): AnsiString;
var
F: File;
Buffer: AnsiString;
Size: Integer;
ReadBytes: Integer;
DefaultFileMode: Byte;
begin
Result := '';
DefaultFileMode := FileMode;
FileMode := 0;
AssignFile(F, FileName);
Reset(F, 1);
if (IOResult = 0) then
begin
Size := FileSize(F);
while (Size > 1024) do
begin
SetLength(Buffer, 1024);
BlockRead(F, Buffer[1], 1024, ReadBytes);
Result := Result + Buffer;
Dec(Size, ReadBytes);
end;
SetLength(Buffer, Size);
BlockRead(F, Buffer[1], Size);
Result := Result + Buffer;
CloseFile(F);
end;
FileMode := DefaultFileMode;
end;
is there any way to reduce more lines?

Answer 1

Like this:
function read_file(const FileName: String): AnsiString;
var
Stream: TFileStream;
begin
Stream := TFileStream.Create(FileName, fmOpenRead);
try
SetLength(Result, Stream.Size);
Stream.ReadBuffer(Pointer(Result)^, Stream.Size);
finally
Stream.Free;
end;
end;
In modern Delphi the TFile class has static methods that can do this as a one liner. Although not directly into an AnsiString.
As well as being shorter I perceive the following additional benefits:
Avoiding Pascal I/O in favour of modern streams.
Error handling by exceptions, taken care of by the stream class.
A single allocation of the string variable as opposed to repeated inefficient re-allocations.
If you must do this with Pascal I0 use a single allocation.
SetLength(Buffer, FileSize(F));
BlockRead(F, Pointer(Result)^, Length(Result), ReadBytes);

Answer 2

If you insist on using old-style I/O, the following function is probably the smallest one you can do and still handle errors appropriately (if appropriately handling errors is to return an empty string).
function read_file(const FileName: String): AnsiString;
var
F: File;
DefaultFileMode: Byte;
begin
DefaultFileMode := FileMode;
try
FileMode := 0;
AssignFile(F, FileName);
{$I-}
Reset(F, 1);
{$I+}
if IoResult=0 then
try
SetLength(Result,FileSize(F));
if Length(Result)>0 then begin
{$I-}
BlockRead(F,Result[1],LENGTH(Result));
{$I+}
if IoResult<>0 then Result:='';
end;
finally
CloseFile(F);
end;
finally
FileMode := DefaultFileMode;
end;
end;