[Tutor] self-modification

[Kent Johnson]

Zsiros Levente wrote:
> I'm a newbie to Python. I wanted to write a graphical interface which 
> would show the built-in documentation (I mean dir() and __doc__ ) of 
> Python. The code shows how far I got before realizing that I had to use 
> some self-modification feature (converting a string to a function or to 
> an object; i'm not sure you would call it self-modification in an 
> interpreted language).
>   
You can convert a string to a function or object using exec and eval but 
often it's better to use Python's introspection capabilities such as 
getattr() and setattr(). For example if you want to convert a string 
received from dir() to the value of the corresponding attribute, use 
getattr(). Can you say more about why you need to convert a string to an 
object?
> I was googling around, and searching in the maillist archives and found 
> this:
> http://mail.python.org/pipermail/tutor/2004-October/032388.html
> Unanswered for two years. Not too promising :)
>   
That post is pretty vague. I'm surprised that there was no followup 
asking for clarification but not surprised that there is no answer.

I don't know of a tutorial on exec and eval but you can find docs here:
http://docs.python.org/ref/exec.html
http://docs.python.org/lib/built-in-funcs.html#l2h-23
> P.S.: I'm new to this mailing list, so I don't know whether it is 
> allowed to send code as attachment. (I didn't found anything about your 
> policy in the subscription site. )  If not, I'm sorry.

Short code snippets such as yours can be sent as an attachment or inline 
in the email. Personally I prefer inline as it makes it easy to reply 
with comments interspersed with the code.

Kent