On Sun, Apr 13, 2014 at 2:56 AM, Chris Angelico <rosuav@gmail.com> wrote:
On Sun, Apr 13, 2014 at 2:21 PM, Andrew Barnert <abarnert@yahoo.com.dmarc.invalid> wrote:
Of course the cost is that you don't get compile-time type checking. But for many programs, that type checking is nearly useless (at least the Java kind; the Haskell kind is more useful).
Aside: I have periodically had bugs where I omit the first argument of a function (in situations where, had it not been first, it would have been marked optional). In C, those sorts of bugs are often caught by the function signature; in Python, they can be, but only if the function takes a fixed number of args. For instance:
void foo(target *destination, const char *msg, int blah=0, int blahblah=0)
If you omit the destination, you get an error back straight away, because a string (const char *) can't be converted into a target. The equivalent in Python, though:
No you don't! If you're stuck in C89 for one reason or another, all you get is a warning(which most programmers ignore anyway). C++ is much more strict in that regard.
def foo(destination, msg, blah=0, blahblah=0):
would happily assign the args one slot earlier, as long as I provided at least one of the optionals. But this is a fairly narrow case; if both those args were mandatory, the mere count of arguments would trip an error. (Albeit at run-time, not compile-time, but until Python goes to actually run the line of code, it can't know that this is the signature anyway.)
ChrisA
PS. Neat trick with dmarc. _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
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