[Tutor] Is my style OK in this elementary student exercise?

[Alan Gauld]

"Angus Rodgers" <angusr at bigfoot.com> wrote

>  (i) trapping the exception StandardError may, for all I know,
> be a daft thing to do;

Not daft but not that common. Mainly because use of eval() 
is kind of frownedoon for security reasons. (See below.)

> (iv) correlatively with (iii), my indentation perhaps looks a
> little extreme (perhaps suggesting a redesign, I don't know);

You can miss out a few else clauses, especially after 
the try/excepts:

-----------
while get_bool("Continue?"): 
    try: key = eval(raw_input("Key value of type " + key_typ.__name__ + ": ")) 
    except StandardError: print "That's not a Python expression!" 

    if not isinstance(key, key_typ): 
       print "That's not a value of type", key_typ.__name__ else: # User has provided
    try: val = eval(raw_input("Object of type " + val_typ.__name__ + ": ")) 
    except StandardError: print "That's not a Python expression!" 

    if not isinstance(val, val_typ): 
       print "That's not an object of type", val_typ.__name__ 
    else: # User has provided an object of the correct type 
       ans[key] = val 
return ans
------------

I'm hoping you know about the security issues around using 
eval with raw_input? The use can input any valid python code 
and it will be evaluated! For experimenting its OK but in 
live code it would be very risky.

HTH,

-- 
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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