On Jul 28, 7:45 pm, Steven D'Aprano <steve-REMOVE- t...@cybersource.com.au> wrote: > On Wed, 28 Jul 2010 08:47:52 -0700, Carl Banks wrote: > > On Jul 28, 7:32 am, Steven D'Aprano <st...@remove-this- > > cybersource.com.au> wrote: > >> On Wed, 28 Jul 2010 09:35:52 -0400, wheres pythonmonks wrote: > >> > Thanks ... I thought int was a type-cast (like in C++) so I assumed I > >> > couldn't reference it. > > >> Python doesn't have type-casts in the sense of "tell the compiler to > >> treat object of type A as type B instead". The closest Python has to > >> that is that if you have an instance of class A, you can do this: > > >> a = A() # make an instance of class A a.__class__ = B # tell it that > >> it's now class B > > >> and hope that it won't explode when you try to use it :/ > > > Type casts in C and non-pathlogical C++ don't modify the object they are > > casting. > > > int (and str, float, etc.) is the closest thing to a type cast in > > Python. > > Perhaps I have been misinformed, but my understanding of C type-casts is > that (where possible), a cast like `int(var)`
(int)var > merely tells the compiler > to temporarily disregard the type of var and treat it as if it were an > int. In other words, it's a compiler instruction rather than a conversion > function. Even if it did, it would still be temporary. The type of the variable remains unchanged. But it doesn't disregard the original type: type casts try to preserve semantic value. (double)1 returns 1.0, which is not only a different bit pattern but a different size. That's exactly what float() does in Python. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
