I need to loop until I hit the end of a file-like object, but I'm not finding an "obvious way to do it", which makes me suspect I'm overlooking something, well, obvious. :-)
I have a stream (in this case, it's a StringIO object, but I'm curious about the general case as well) which stores an unknown number of records in "<length><data>" format, e.g.:
data = StringIO("\x07\x00\x00\x00foobar\x00\x04\x00\x00\x00baz\x00")
Now, the only clear way I can imagine to read this is using (what I think of as) an initialized loop, which seems a little un-Pythonic:
len_name = data.read(4)
while len_name != "":
len_name = struct.unpack("<I", len_name)[0]
names.append(data.read(len_name))
len_name = data.read(4)
In a C-like language, I'd just stick the read(4)
in the while
's test clause, but of course that won't work for Python. Any thoughts on a better way to accomplish this?
You can combine iteration through iter() with a sentinel:
for block in iter(lambda: file_obj.read(4), ""):
use(block)