How do I wrap a string in a file in Python?

For Python 2.x, use the StringIO module. For example:

>>> from cStringIO import StringIO
>>> f = StringIO('foo')
>>> f.read()
'foo'

I use cStringIO (which is faster), but note that it doesn't accept Unicode strings that cannot be encoded as plain ASCII strings. (You can switch to StringIO by changing "from cStringIO" to "from StringIO".)

For Python 3.x, use the io module.

f = io.StringIO('foo')

In Python 3.0:

import io

with io.StringIO() as f:
    f.write('abcdef')
    print('gh', file=f)
    f.seek(0)
    print(f.read())

The output is:

'abcdefgh'

This works for Python2.7 and Python3.x:

io.StringIO(u'foo')

If your file-like object is expected to contain bytes, the string should first be encoded as bytes, and then a BytesIO object can be used instead. In Python 3:

from io import BytesIO

string_repr_of_file = 'header\n byline\n body\n body\n end'
function_that_expects_bytes(BytesIO(bytes(string_repr_of_file,encoding='utf-8')))

Two good answers. I’d add a little trick — if you need a real file object (some methods expect one, not just an interface), here is a way to create an adapter:

http://www.rfk.id.au/software/filelike/

How do I wrap a string in a file in Python?

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