I have this Python tool written by someone else to flash a certain microcontroller, but he has written this tool for Python 2.6 and I am using Python 3.3.
So, most of it I got ported, but this line is making problems:
data = map(lambda c: ord(c), file(args[0], 'rb').read())
The file
function does not exist in Python 3 and has to be replaced with open
. But then, a function which gets data
as an argument causes an exception:
TypeError: object of type 'map' has no len()
But what I see so far in the documentation is, that map
has to join iterable types to one big iterable, am I missing something?
What do I have to do to port this to Python 3?
In Python 3, map
returns an iterator. If your function expects a list, the iterator has to be explicitly converted, like this:
data = list(map(...))
And we can do it simply, like this
with open(args[0], "rb") as input_file:
data = list(input_file.read())
rb
refers to read in binary mode. So, it actually returns the bytes. So, we just have to convert them to a list.
Quoting from the open
's docs,
Python distinguishes between binary and text I/O. Files opened in binary mode (including 'b' in the mode argument) return contents as bytes objects without any decoding.