Question

Is there a way to import a Python module stored in a cStringIO data structure vs. physical disk file?

It looks like “imp.load_compiled(name, pathname[, file])” is what I need, but the description of this method (and similar methods) has the following disclaimer:

Quote: “The file argument is the byte-compiled code file, open for reading in binary mode, from the beginning. It must currently be a real file object, not a user-defined class emulating a file.” [1]

I tried using a cStringIO object vs. a real file object, but the help documentation is correct – only a real file object can be used.

Any ideas on why these modules would impose such a restriction or is this just an historical artifact?

Are there any techniques I can use to avoid this physical file requirement?

Thanks,
Malcolm

[1] http://docs.python.org/library/imp.html#imp.load_module

Answer 1

Something like this perhaps?

import types
import sys

src = """
def hello(who):
    print 'hello', who
"""

def module_from_text(modulename, src):
    if modulename in sys.modules:
        module = sys.modules[modulename]
    else:
        module = sys.modules[modulename] = types.ModuleType(modulename)
    exec compile(src, '<no-file>', 'exec') in module.__dict__
    return module

module_from_text('flup', src)
import flup
flup.hello('world')

Which prints:

hello world

EDIT:

Evaluating code in this way treads nearish the realm of writing custom importers. It may be useful to look at PEP 302, and Doug Hellmann’s PyMOTW: Modules and Imports.