[Edu-sig] interactive vs compiled from file

Dethe Elza delza at livingcode.org
Sat Aug 4 05:13:05 CEST 2007

On 3-Aug-07, at 5:35 PM, kirby urner wrote:

> I guess it boils down to a quibble over the verb "echoing" -- a source
> of confusion for me.

I'm not attached to "echoing," that's just what it is called in the  
shell (and the shell is not always right).  I just wanted to clarify  
that we the eval is still happening.

> In the first eval above, the output of the eval looks a lot like  
> the input
> (hence "echo").
> But most expressions evaluate to a result that's different, so what
> you call "default echoing" I call "default printing of the results of
> evaluation".

Sure, that's fine.

> We're agreeing that what's happening is always an eval, and we're
> agreeing that the print part of REPL could be suppressed, leading
> to REL instead.


>>>>> sys.displayhook = noecho
>>>>> 'abc'
>>>>> sys.displayhook = echo
>>>>> 'abc'
>> abc
>>>>> _
>> <built-in function displayhook>
>>>>> sys.displayhook = echo_and_assign
> This doesn't very newbie-accessible to me.

No.  That wouldn't be a first lesson.  But maybe for a more  
precocious student, to keep them busy while you get the others in the  
class get caught up...

>> It's all fun and games, until someone loses their ribs.  ;-)
> However I think these are *advanced* games.

Agreed.  I got carried away playing with it.  The point is that  
Python has these hooks all over the place, and sometimes when we  
think we need to create a new version of the interpreter, all that is  
needed is to play with the hooks a bit.

> The original confusion, as I understood it, was "Python in shell mode"
> versus "Python running a .py file".  I think we might explain that  
> "shell
> mode" is a special script that implements an interactive evaluation  
> loop,
> a feature we much appreciate about Python.
> Anyway, I'm not here to say "my way or the highway".  If you or Andre
> want a "dead parrot mode", why not?  Maybe for some students, the  
> light
> will go on and all confusions will dissipate -- which I think is  
> our shared
> goal.

Absolutely.  I think we can agree to agree.


"Any idea that couldn't stand a few decades of neglect is not worth  
anything." --Gabriel Garcia Marquez

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