I'm trying to run the following code in python3, but it has been written for I'm pretty sure python2:
f = open(filename, 'r')
self.lines = f.readlines()
f.close()
if self.lines[-1] != "\n" :
self.lines.append("\n")
But I'm getting the following error:
File "randline.py", line 32
if self.lines[-1] != "\n" :
^
TabError: inconsistent use of tabs and spaces in indentation
Can you help me figure out the correct syntax?
Python 2 allows you to mix spaces and tabs. so you can have indentation like:
def foo():
[this is a tab it counts like eight spaces ]for each in range(5):
[this is a tab it counts like eight spaces ][space][space]print(each)
[space][space][space][space][space][space][space][space]print("Done!")
Line 2 and line 4 will in Python 2 have the same indentation level, but line 2 will do it with a tab, and line 4 will do it with spaces. Printed to the console, it will look like this:
def foo()
for each in range(5):
print(5)
print("Done!")
But most editors allow you to set how many spaces a tab should be. Set it to four, and you get this:
def foo()
for each in range(5):
print(5)
print("Done!")
The indentation is still the same, but now it looks like the indentation is wrong!
Python 3 therefore do not allow the same indentation level (ie line 2 and 4) to be indented in different ways. You can still mix tabs and spaces, but not in the same indentation level. This means that
def foo():
[this is a tab it counts like eight spaces ]for each in range(5):
[this is a tab it counts like eight spaces ][space][space]print(each)
[this is a tab it counts like eight spaces ]print("Done!")
will work, and so will
def foo():
[this is a tab it counts like eight spaces ]for each in range(5):
[space][space][space][space][space][space][space][space][space][space]print(each)
[this is a tab it counts like eight spaces ]print("Done!")
The only way to make that the only way you can make the indentation look weird is of you set a tab to be more than eight spaces, and then the indentation not only looks obviously incorrect, you'll notice that a tab will indent 12 spaces (in the below example) so you realize you insert a tab, and not four spaces.
def foo():
for each in range(5):
print(each)
print("Done!")
Of course, the solution to all your problems is as written in the comments, to never use tabs. I'm not sure why Python 3 still allows tabs at all, there is no good reason for that, really.
four spaces as indent as a single construct. There are other reasons too, which is why the subject was contentious for so long, and why I still code in tabs even though I acknowledge that ship has sailed for Python.