Python Programming Language :: get a list from a string


	get a list from a string Hi, I have a string "distances = [[1,1,1,1],[2,2,2,2]]". I want to create a variable called distances whose value is the list [[1,1,1,1],[2,2,2,2]]. How can I go about that? I know I can use setattr, but how do I create the list from the string? Regards, Simon On Jun 7, 3:34 am, simon kagwe <simonka@yahoo.com> wrote: > Hi, > I have a string "distances = [[1,1,1,1],[2,2,2,2]]". I want to create a > variable called distances whose value is the list [[1,1,1,1],[2,2,2,2]]. How can > I go about that? I know I can use setattr, but how do I create the list from the > string? > Regards, > Simon exec("distances = [[1,1,1,1],[2,2,2,2]]") ~Sean simon kagwe wrote: > Hi, > I have a string "distances = [[1,1,1,1],[2,2,2,2]]". I want to create a > variable called distances whose value is the list [[1,1,1,1],[2,2,2,2]]. How can > I go about that? s = "distances = [[1,1,1,1],[2,2,2,2]]" exec(s) - Josef > exec("distances = [[1,1,1,1],[2,2,2,2]]") Wow! So simple! Thanks a lot. :-) On Jun 7, 6:06 am, simon kagwe <simonka@yahoo.com> wrote: > > exec("distances = [[1,1,1,1],[2,2,2,2]]") To be clear, exec is not a function; it's a statement. That means it can't be used in lambda functions, for example. > Wow! So simple! but dodgy, as it'll execute any python code. - Hide quoted text - > Thanks a lot. :-) On Thu, 07 Jun 2007 11:06:54 +0000, simon kagwe wrote: >> exec("distances = [[1,1,1,1],[2,2,2,2]]") > Wow! So simple! > Thanks a lot. :-) Yes, and when you embed this in your web-application, using data gathered from a web-form, the black-hat hackers will thank you for the security hole too. Surely a much better solution would be NOT to start with a string like "distances = [[1,1,1,1],[2,2,2,2]]" in the first place? Where does that string come from? If it comes from the user, at run-time, using exec is a MAJOR security hole. If it comes from the source code, then WHY??? I wish exec and eval were hidden away in a module so they were harder (but not impossible) to get to. Because I'm paranoid, I wish importing that module would print an warning saying "Are you MAD??? Don't do this!!!". I wish even more that Python would come with a built-in "make a list from a list representation" function, but that at least is fairly easy to create: you can modify Here is a discussion about just how hard (that is, probably impossible) it is to make eval safe: http://effbot.org/zone/librarybook-core-eval.htm Ah, sorry, pre-mature sending. Stupid keyboard accelerators :( To finish the sentence I was trying to write: On Thu, 07 Jun 2007 22:39:41 +1000, Steven D'Aprano wrote: > I wish even more that Python would come with a built-in "make a list from a > list representation" function, but that at least is fairly easy to create: > you can modify ... Fredrik Lundh's safe-eval function: http://online.effbot.org/2005_11_01_archive.htm -- Steven.