My first Python program

[Seebs]

On 2010-10-12, MRAB <python at mrabarnett.plus.com> wrote:
> The code does require Python 2 and the use of except ... as ... requires 
> at least version 2.6.

Whoops.

> Line 51

> The __init__ method should always return None. There's no need to be 
> explicit about it, just use a plain "return".

The real issue here is that I was assuming that open('nonexistent') returned
None rather than raising an exception.

> The error message says:

>      "Couldn't open %s to read a template."

> but it's opening the file for writing.

Ahh, my famed attention to detail strikes again. :)

> You can't really rely on the destructor __del__ being called.

Interesting.  Do I just rely on files getting closed?

> Line 333

> Shouldn't you be checking that the name of the attribute you're setting 
> doesn't clash with one of the existing attributes? Are you sure that a 
> dict wouldn't be a better idea?

Actually, not sure at all.  There's a sort of gradual evolution going on
here, in that I was trying to avoid having a separate dict that I had to
populate with a bunch of stuff -- thus the switch to a hand-written
__getitem__.  What I probably ought to do/have done is use a dict first,
and set things in the dict from here, then check the dict first, then
regular getattr, and so on.

> Line 447
>
> The form:
>
>      except ... as ...
>
> is in Python versions >= 2.6, but not earlier.

Oops.  Is there a way to interact with the caught exception in earlier
Python?

> This use of del just deletes the name from the namespace and won't 
> necessarily call the __del__ method of the 'source' object. It's better 
> to rely on something more explicit like a 'close' method. (If you can't 
> be sure which version of Python it'll use then context managers are 
> probably out anyway!)

Okay, good to know.  I'll fix that.

-s
-- 
Copyright 2010, all wrongs reversed.  Peter Seebach / usenet-nospam at seebs.net
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