typecheck has kinda been on the back burner for…oh…the last few months, let’s say. In my defense, I’ve been a bit busy, primarily with the “travelling around Europe” thing. However, I’ve also been hard at work at a PEP to add function annotations to Python 3.0 — a project I hope to have more news on shortly.

Today, however, typecheck took a good-size surge forward. The main thrust of the 40+ commits were to bring typecheck more into line with the style of function annotations that Python 3.0 will have. To this end:

  • In past releases of typecheck, it’s been required that every parameter have a type annotation. In 0.4, this will change; type annotations, now done exclusively through keyword arguments, will be completely optional. To wit, with typecheck < 0.4, this:

    @accepts(Number, Number)
def foo(a, b):
    ...

    becomes

    @accepts(a=Number, b=Number)
def foo(a, b):
    ...

  • Since types are now optional, there’s no need for things like Self(), which will go away

  • The dual spellings of types for *vargs and **kwargs are going bye-bye. Whereas in typecheck < 0.4 these were equivalent

    @accepts(vargs=Number)
def sum(*vargs):
    ....

@accepts(vargs=[Number])
def sum(*vargs):
    ....

    In typecheck 0.4, the latter signature will expect that each argument to sum is a list of Numbers.

In addition, the Xor(), Not() and Any() annotation classes are going away; they’re being spun off into a separate type_algebra package that will be shipped in typecheck’s contrib directory. More on that later, too.