Yet Another Newbie Question (YANQ)

[Simon Brunning]

> From:	David A. [SMTP:man_at_moon at hotmail.com]
> I have this problem:
> 
> >>> a='a'
> >>> prt='print'
> >>> t=prt+' '+a
> >>> t
> 'print a'
> 
> now when I try to:
> >>> eval(t)
> Traceback (innermost last):
>   File "<pyshell#18>", line 1, in ?
>     eval(t)
>   File "<string>", line 1
>     print a
>         ^
> SyntaxError: invalid syntax
> 
> can someone explain me what I am doing wrong! Why can't I use eval(print)?
> Any help is welcome!
 
eval evaluates a Python expression - 'print a' isn't an expression. Use eval
like this:

>>> spam = '1 + 4'
>>> eggs = eval(spam)
>>> print eggs
5

What *you* want is 'exec'. try this:

>>> a = 'a'
>>> prt='print'
>>> t=prt+' '+a
>>> t
'print a'
>>> exec(t)
a

Cheers,
Simon Brunning
TriSystems Ltd.
sbrunning at trisystems.co.uk

On two occasions I have been asked (by members of Parliament!), 'Pray, Mr.
Babbage, if you put into the machine wrong figures, will the right answers
come out?' I am not able rightly to apprehend the kind of confusion of ideas
that could provoke such a question. - Charles Babbage




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