This post originated from an RSS feed registered with Agile Buzz by James Robertson. Original Post: Keith Ray on type checking Feed Title: Cincom Smalltalk Blog - Smalltalk with Rants Feed URL: http://www.cincomsmalltalk.com/rssBlog/rssBlogView.xml Feed Description: James Robertson comments on Cincom Smalltalk, the Smalltalk development community, and IT trends and issues in general. Latest Agile Buzz Posts Latest Agile Buzz Posts by James Robertson Latest Posts From Cincom Smalltalk Blog - Smalltalk with Rants

Now the dynamic-typing people say that, in practice, it's very rare to pass a string into a function that expects an integer, or vice versa. (I have rarely experienced such a problem in C when trying to do manual refactoring, but that was quickly detected via crashes when running tests and the application.) However, there is a big loop-hole of type-checking in any language that has polymorphism, whether dynamically-typed or staticly-typed: your functions may require arguments whose type implement a certain interface (or be a subclass of a certain class), but there is nothing that forces the objects being passed into those functions to implement anything meaningful. In practice, this isn't a big problem - in fact, it happens so rarely that static type-checking advocates don't even think of this problem.

It's a good article, and points out some of the things that manifest typing advocates rarely consider - the holes in the systems that they claim are safer...