inplace text filter - without writing file

[Sayth Renshaw]

On Sunday, 2 October 2016 16:19:14 UTC+11, Sayth Renshaw  wrote:
> 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

Aargh, half solved it, now it works except I am creating a list as the yielded item and lxml doesn't accept list it wants the file.

def return_files(file_list):
    """
    Take a list of files and return file when called.

    Calling function to supply attributes
    """
    for filename in sorted(file_list):
        file = os.path.join(dir_path, filename)
        with open(file, 'r') as fd:
            data = fd.read().splitlines(True)
            if data[0].startswith('<!--'):
                print(data[1:])
                yield data[1:]
            else:
                yield data[0:]

Cheers

Sayth