Convert list to file object without creating an actual file.

[Bart Kastermans]

I have written a little program that takes as input a text file,
converts
it to a list with appropriate html coding (making it into a nice
table).
Finally I want to upload this list as a textfile using ftp.

If homeworkhtml contains the list of lines;
e.g. homeworkhtml = ["<table>", "<tr>", "<td>", "test", "</td>" .....

I want to call:
ftp.storlines("STOR " + filename, homeworkhtml)

which gives me the error
Traceback (most recent call last):
File "./testhw.py", line 67, in ?
ftp.storlines("STOR " + filename, homeworkhtml)
File "/System/Library/Frameworks/Python.framework/Versions/2.3/lib/
python2.3/ftplib.py", line 428, in storlines
AttributeError: 'list' object has no attribute 'readline'

Expected since homeworkhtml is in fact not a file. Is there a way
to convert this list to a file object without first writing it to disc
and
then opening the resulting file?

Best,
Bart

[Benjamin]

On Jan 24, 8:57 pm, Bart Kastermans <[e-mail]:

I have written a little program that takes as input a text file,
converts
it to a list with appropriate html coding (making it into a nice
table).
Finally I want to upload this list as a textfile using ftp.

If homeworkhtml contains the list of lines;
e.g. homeworkhtml = ["<table>", "<tr>", "<td>", "test", "</td>" .....

I want to call:
ftp.storlines("STOR " + filename, homeworkhtml)

which gives me the error
Traceback (most recent call last):
File "./testhw.py", line 67, in ?
ftp.storlines("STOR " + filename, homeworkhtml)
File "/System/Library/Frameworks/Python.framework/Versions/2.3/lib/
python2.3/ftplib.py", line 428, in storlines
AttributeError: 'list' object has no attribute 'readline'

Perhaps what you want is StringIO. It lets your pretend a string is a
file so ftplib won't choke. You'll have to convert your list to a
string, though (perhaps with join):
from cStringIO import StringIO
fake_file = StringIO("".join(my_list))

>
Expected since homeworkhtml is in fact not a file. Is there a way
to convert this list to a file object without first writing it to disc
and
then opening the resulting file?

Best,
Bart

[Steven D'Aprano]

On Thu, 24 Jan 2008 18:57:58 -0800, Bart Kastermans wrote:

I have written a little program that takes as input a text file,

....

Expected since homeworkhtml is in fact not a file. Is there a way to
convert this list to a file object without first writing it to disc and
then opening the resulting file?

The StringIO module is your friend, together with a couple of basic
Python techniques.

>>alist = ["<table>\n", " <tr>\n",

.... " <td>", "Nobody expects the Spanish Inquisition!",
.... "</td>\n", " </tr>\n", "</table>\n"]

>>print ''.join(alist) # but strings don't have a readlines method...

<table>
<tr>
<td>Nobody expects the Spanish Inquisition!</td>
</tr>
</table>

>>>
f = StringIO.StringIO()
f.writelines(alist)
f.getvalue()

'<table>\n <tr>\n <td>Nobody expects the Spanish Inquisition!</td>\n
</tr>\n</table>\n'

>>f.seek(0) # don't forget to reset the file pointer!
print f.read() # also has readlines

<table>
<tr>
<td>Nobody expects the Spanish Inquisition!</td>
</tr>
</table>


--
Steven