FAQ: How do I calculate what quoted strings and numbers mean?

[p.lavarre at ieee.org]

> A FAQ that discusses good ways to handle Python-like literals and
> expressions would definitely be a useful addition to the FAQ.  if nobody
> else does anything about it, I'll get there sooner or later.

Thank you.

>  > eval(source, {'builtins': {}}) works enough like an evaluator of
>  > literals to ...
>
> eval(source, {'builtins': {}}) doesn't prevent you from using built-ins,
> though.  it's spelled __builtins__, not builtins:
>
>  >>> eval("len('10')", {"builtins": {}})
> 2
>  >>> eval("len('10')", {"__builtins__": {}}
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
>    File "<string>", line 1, in <module>
> NameError: name 'len' is not defined

Grin.  Indeed, newbie me, I didn't know that either, thank you.

I was happy enough when I saw an improvement like:

>>> import os
>>> result = eval("os.system('pwd')")
.../Desktop
>>> result = eval("os.system('pwd')", {"whatever": {}})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1, in <module>
NameError: name 'os' is not defined
>>>

Now I fear that I must have copied the misspelled builtins from some
page that's still out there somewhere misleading people ...