checktype 1.0.0

Intuitive and minimalistic type checking for Python objects

Checktype allows simple checking of Python object formats.

E.g. make sure that an object is a list of tuples, each tuple with an int, a string and a float. This would be expressed as:

use_strict() # to activate checktype
checktype([(1, 'hello', 2.0)], "[(1, 's', 1.0)]")

Checktype can catch many programming errors by validating your complex datastructures. It is particularily helpful when refactoring programs.Checktype has a very intuitive type system that mimics the way you define your own Python objects.

Published as a pip package at https://pypi.python.org/pypi/checktype/

Usage examples:

from checktype import checktype, use_strict # pip install checktype

# 'activates' checktype
# you need to explicitly configure checktype's 'strict' mode,
# else it will do nothing (by default, to save cpu time)
# it's common to specify it in tests
use_strict()

# checktype only provides a single function, that takes two arguments.
# the first one is the python object you want to test;
# the second one is an 'object specification' (spec), that mimics the way
# objects are represented in Python. This spec is a string representation of
# a python object. For example, to check that 12 is an int or 'hello' is a str:
checktype(12, '1')
checktype('hello', " 's' ") # note that you have to put quotes around the str

# It is customary to consistently use the same placeholders in the spec (e.g. 1 for ints, s for string), but any value of the right type will work:
checktype(12, '12')
checktype(12, '12345')

# A list of exactly 3 floats is specified as [1.,1.,1.]
checktype([1.0,2.0,3.0], '[1.,1.,1.]')

# To match a variable-length list of ints, use [1..]
checktype([1,2,3], '[1..]')

# And so on for tuples,
checktype((1,2,3), '(1,1,1)')
checktype((1,2,3), '(1..)')
# dictionnaries,
checktype({11:2},  '{1:1}')
checktype({11:2, 12: 3},  '{1:1}')
# and sets
checktype({11, 2},  '{1}')

# use the ? wildcard if you don't want to check for a specific part
checktype({11:2, 12: "a", 13:(3,4)},  '{1:?}')

# more complex examples
checktype({11: (2,3), 12: (4,"5")}, '{ 1: (1,?)}')
checktype([(2, "asdf"),(-12, "asfwe"),(1,"")], "[(1,'s')..]")
checktype([(1, 'hello', 2.0)], "[(1, 's', 1.0)]")