Implement a `StrToResID` function

[delphidabbler]

There's already a ResIDToStr function. It's inverse would be useful if, when presented with a suitably formatted string it could be converted back to a resource ID.

Parsing rules:

• If string starts with # and rest is numeric, then the resource ID is numeric and can be created with MakeIntResource.
• Otherwise resource ID is just a Pointer to the string itself, which should be OK providing the string passed as parameter remains in scope.

[delphidabbler]

Possible code, untested:

function IsValidResIDStr(Str: string): Boolean;
begin
  Result := False;
  if Length(Str) = 0 then
    Exit;
  if Str[1] = '#' then
  begin
    if Length(Str) = 1 then
      Exit;
    for var I := 2 to Length(Str) do
    begin
      if not TCharacter.IsNumeric(Str[I]) then
        Exit;
    end;
    Result := True;
  end
  else
    Result := True;
end;

function StrToResID(Str: string): PChar;
begin
  if not IsValidResIDStr(Str) then
    raise Exception.Create('...');
  if Str[1] = '#' then
  begin
    var NStr := RightStr(Str, Length(Str) - 1);
    var N := StrToInt(NStr);
    Result := MakeIntResource(N);
  end
  else
    Result := PChar(Str);
end;

Notice how the code is much clearer with function IsValidResIDStr defined, without too much code being run twice. We might as well make that routine public too.