[Tutor] re-directing print statements in exec

[Jeff Shannon]

Toby Donaldson wrote:
> Hi all,
> 
> I am wondering if there is any easy way to make a print statement in an 
> exec statement get sent to a string instead of the console. For instance,
> 
>>>>  prog = """
> r = 5
> print 3.14 * r ** 2
> """
>>>>  exec prog
> 78.5
> 
> The result gets printed to the console. But instead, I'd like it to be 
> in a string.
> 
> Any suggestions?

First off, I'd suggest just using a function instead of exec.  ;)

def prog():
     r = 5
     return 3.14 * r**2

result = prog()

Of course, it'd probably be better to pass r in as a parameter, and to 
rename the function so that it's meaningful...

def circle_area(r):
     return 3.14 * (r**2)

result = circle_area(5)

There are *very* few situations in which exec is truly the most 
desirable tool, and many situations in which it creates programs that 
are actively dangerous.  The use of exec and its cousin eval() should 
always be considered to be deep black magic -- it is not suitable (nor 
intended for) everyday use.  Unless you're writing an interactive 
shell replacement or a code debugger or some such, I *strongly* 
recommend against using exec.

Jeff Shannon
Technician/Programmer
Credit International