Joining Lists and Splitting Strings

Question

I have some previous experience with C++ and just getting started up with Python. I read this text from Dive into Python :

In my experience, a general idea is, if you want to perform an operation on object 'O', you call a method on that object to do it.

Eg. If I have a list object, and I want to get summation of all elements, I would do something like :

listObject.getSumOfAllElements()

However, the call given in above book excerpt looks a little odd to me. To me this would make more sense :

return (["%s=%s" % (k, v) for k, v in params.items()]).join(";")

i.e. join all the elements of the list as a string, and here, use this parameter ';' as a delimiter.

Is this a design difference or just syntactically a little different than what I am thinking ?

Edit:

For completion, the book says this a little later :

Yes, it's kind of backwards as the ";" is your object here, on which you're performing a method. — MKesper, Nov 24 '15 at 12:32
Do you mean to ask why is it `string.join(list)` instead of `list.join(string)`? — Bhargav Rao, Nov 24 '15 at 12:33
Aaah thanks @BhargavRao It has detailed explanation already on the page you posted. Should I raise this to be closed or plain delete it ? — Amit Tomar, Nov 24 '15 at 12:39
@AmitTomar Nope. Leave it as it is. Other's will benefit from this. thefourtheye's answer is good. Do accept it if you also feel so. — Bhargav Rao, Nov 24 '15 at 12:40

score 5 · Accepted Answer · answered Nov 24 '15 at 12:29

Is this a design difference or just syntactically a little different than what I am thinking?

Yes, I think it is by design. The join function is intentionally generic, so that it can be used with any iterable (including iterator objects and generators). This avoids implementing join for list, tuple, set etc separately.

Joining Lists and Splitting Strings

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