Is Python type safe?

Question

According to Wikipedia

Computer scientists consider a language \"type-safe\" if it does not allow operations or conversions that violate the rules of the

Answer 1

assume that you have a function sum, taking two arguments if arguments are un-typed (can can anything) then... well... that is unacceptable for any serious software engineer working on real life large systems here is why:

1. naive answer would be "compiler is your friend". despite being about 65 years old, this is true and hey, this is not only about having static types! ide(s) use compiler services for a lot of things, which, for average joe programmer look like magic... (code completion, design time (editing) assistance, etc
2. o more realistic reason consists in something completely unknown to developers without a strong background in computer science and more, in software engineering. there are 3 axes of scalability: a. design/write and deploy, b. runtime & c. maintain time, based on refactoring. who do you think is the most expensive one? being clearly recurring on any real life serious system? the third one (c). in order to satisfy (c), you need to do it safe. in order to do any safe refactoring, you need to have unit testing AND coverage testing (so you can estimate the level of coverage your unit testing suite covers) - remember, when something is not automatically tested, it will break (at run time, late in the cycle, at customers site, you name it) - SO, in order to have a decent product, you need to have decent unit testing and test coverage

now, let's get to our intellectually challenging function (sum). is sum(a,b) does not specify the types of a and b, there is no way to do decent unit testing. tests like assent sum(1,1) is 2 IS A LIE, because it does not cover anything but assumed integer arguments. in real life, when a and b are type hermaphrodites, then there is no way to write real unit testing against function sum! various frameworks even pretend to derive test coverage results from crippled test cases as the one described above. that is (obvious) another LIE.

that's all i had to say! thanks for reading, the only reason i posted this is, perhaps, to make you think of this and, maybe (MAYBE..) one day to do software engineering...