Python vs. C#

Duncan Booth duncan at NOSPAMrcp.co.uk
Tue Aug 12 10:38:56 CEST 2003


"Joe Cheng" <code at joecheng.com> wrote in
news:Jq%Za.8237$M6.632214 at newsread1.prod.itd.earthlink.net: 

> Java and C# have static strong typing.
> 
> Python has dynamic strong typing.  So, if you can keep the types of
> your objects straight without the help of the compiler, you get the
> benefits of a concise syntax while enjoying type safety at runtime.
> 
> Someone correct me if I've gotten it wrong...
> 
You have it about right. C# lets you define functions that take arguments 
of any type by boxing them as objects. However, to perform almost any 
operation on these values you have to cast them back to their original 
type. So a function that takes two objects and adds them together can't 
work unless you know the type you expected the objects to be. You cannot 
just add two objects, even if they are of the same type, you have to cast 
(unbox) them from object back to their real type (and you have to get that 
type *exactly* right, you can't for example unbox a short as an int) and 
then operate on them.

[A couple of operations work directly on objects, you can convert any 
object to a string, and compare objects for equality directly].

Python on the other hand will let you do something like adding two objects 
together, it will perform some permitted conversions automatically, e.g. 
extending int to float, but it won't attempt to do weird things like parse 
a string into a number, or for that matter automatically convert a number 
to a string.

Both languages are strongly typed. The drawback with C# is mainly that you 
have to keep telling the language things that both you and the compiler 
already know. If I have an ArrayList filled with strings, and I want to 
pass one of them to a function taking a string argument, I have to 
explicitly cast the element of the ArrayList back to string. If the cast 
fails at runtime I get an exception. Why can the compiler not put that cast 
in silently and give me the same exception at runtime?

-- 
Duncan Booth                                             duncan at rcp.co.uk
int month(char *p){return(124864/((p[0]+p[1]-p[2]&0x1f)+1)%12)["\5\x8\3"
"\6\7\xb\1\x9\xa\2\0\4"];} // Who said my code was obscure?




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