inplace text filter - without writing file

[Sayth Renshaw]

On Sunday, 2 October 2016 12:14:43 UTC+11, MRAB  wrote:
> On 2016-10-02 01:21, Sayth Renshaw wrote:
> > Hi
> >
> > I have a fileobject which was fine however now I want to delete a line from the file object before yielding.
> >
> > def return_files(file_list):
> >     for filename in sorted(file_list):
> 
> When joining paths together, it's better to use 'os.path.join'.
> 
> >         with open(dir_path + filename) as fd:
> >              for fileItem in fd:
> >                  yield fileItem
> >
> > Ned gave an answer over here http://stackoverflow.com/a/6985814/461887
> >
> > for i, line in enumerate(input_file):
> >     if i == 0 or not line.startswith('#'):
> >         output.write(line)
> >
> > which I would change because it is the first line and I want to rid <!--
> >
> > for i, line in enumerate(input_file):
> >     if line.startswith(<!--'):
> >         output.write(line)
> >
> > However I do not want to write the file I want to restore all the enumerated files back to the fileItem I need to yield.
> >
> > How do I do this?
> >
> You use the logic of the answer from StackOverflow in your 
> 'return_files' function:
> 
> def return_files(file_list):
>      for filename in sorted(file_list):
>          with open(dir_path + filename) as fd:
>              for fileItem in fd:
>                  if keep_item(fileItem):
>                      yield fileItem
> 
> 
> If you need to know the line number when deciding whether to keep a 
> line, use enumerate too:
> 
> def return_files(file_list):
>      for filename in sorted(file_list):
>          with open(dir_path + filename) as fd:
>              for i, fileItem in enumerate(fd):
>                  if keep_item(fileItem, i):
>                      yield fileItem

I just can't quite get it.

def return_files(file_list):
    for filename in sorted(file_list):
        file = os.path.join(dir_path, filename)
        print(file)
        with open(file) as fd:
            print(fd)
            for fileItem in fd:
                print(fileItem)
                for line in fileItem:
                    print(line[0])
                    if line.startswith('<!--'):
                        print(line[1:])
                        yield line[1:]
                    else:
                        yield line[:]

I maybe over baking it but just not getting it right.

Sayth