matching a string to extract substrings for which some function returns true

[Steven D'Aprano]

On Tue, 22 Nov 2005 16:57:41 +0530, Amit Khemka wrote:

> Hello All,
> 
> say you have some string: "['a', 'b', 1], foobar ['d', 4, ('a', 'e')]"
> Now i want to extract all substrings for which
> "isinstance(eval(substr), list)" is "True" .

That's an awfully open-ended question. Is there some sort of structure to
the string? What defines a substring? What should you get if you extract
from this string?

"[[[[[]]]]]"

Is that one list or five?


> now one way is to walk through the whole sample string and check the
> condition, 

Yes. Where does the string come from? Can a hostile user pass bad strings
to you and crash your code?


-- 
Steven.