[Tutor] Fwd: grave confusion

[Danny Yoo]

---------- Forwarded message ----------
From: Danny Yoo <dyoo at hashcollision.org>
Date: Mon, Oct 6, 2014 at 11:23 AM
Subject: Re: [Tutor] grave confusion
To: Clayton Kirkwood <crk at godblessthe.us>


> Well the guide certainly doesn't suggest that the read is one character at a time, it implies one line at a time. However, it's hard to argue against the one character because that is what the output is looking at. I thought it would read one line in per iteration. Why didn't they call it readchar()?


I think you might still be confused.


Here, let's look at it again from a different angle.

####################
for line in file.readline():
    ...
####################



I'm going to make a small change to this:

####################
seq = file.readline()
for line in seq:
    ...
####################

I've introduced a temporary variable.  This should preserve the rough
meaning by just giving a name to the thing we're walking across.



One more change:

####################
seq = file.readline()
for thing in seq:
    ...
####################

Again, meaning preserving, if we change every instance of "line" in
"..." with "thing".  But "thing" is a poor name for this as well.
What's its type?

If seq is a string, then thing has to be a character.  Let's change
the code one more time.


######################
seq = file.readline()
for ch in seq:
    ...
#######################




Contrast this with:

#######################
for line in file.readlines():
    ...
#######################

This has a *totally* different meaning.  The "delta" is a single
character in terms of the physical source code, but in terms of what
the program means, high impact.