Predefined Data Types in parse

behave uses the parse module (inverse of Python string.format) under the hoods to parse parameters in step definitions. This leads to rather simple and readable parse expressions for step parameters.

# -- FILE: features/steps/type_transform_example_steps.py
from behave import given

@given('I have {number:d} friends')  #< Convert 'number' into int type.
def step_given_i_have_number_friends(context, number):
    assert number > 0
    ...

Therefore, the following parse types are already supported in step definitions without registration of any user-defined type:

Type	Characters Matched	Output Type
w	Letters and underscore	str
W	Non-letter and underscore	str
s	Whitespace	str
S	Non-whitespace	str
d	Digits (effectively integer numbers)	int
D	Non-digit	str
n	Numbers with thousands separators (, or .)	int
%	Percentage (converted to value/100.0)	float
f	Fixed-point numbers	float
e	Floating-point numbers with exponent e.g. 1.1e-10, NAN (all case insensitive)	float
g	General number format (either d, f or e)	float
b	Binary numbers	int
o	Octal numbers	int
x	Hexadecimal numbers (lower and upper case)	int
ti	ISO 8601 format date/time e.g. 1972-01-20T10:21:36Z	datetime
te	RFC2822 e-mail format date/time e.g. Mon, 20 Jan 1972 10:21:36 +1000	datetime
tg	Global (day/month) format date/time e.g. 20/1/1972 10:21:36 AM +1:00	datetime
ta	US (month/day) format date/time e.g. 1/20/1972 10:21:36 PM +10:30	datetime
tc	ctime() format date/time e.g. Sun Sep 16 01:03:52 1973	datetime
th	HTTP log format date/time e.g. 21/Nov/2011:00:07:11 +0000	datetime
tt	Time e.g. 10:21:36 PM -5:30	time