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-rw-r--r--gn3/function_helpers.py36
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+"""
+This module will contain helper functions that should assist in maintaining a
+mostly functional way of programming.
+
+It will also contain miscellaneous functions that can be used globally, and thus
+do not fit well in any other module.
+
+FUNCTIONS:
+compose: This function is used to compose multiple functions into a single
+ function. It passes the results of calling one function to the other until
+ all the functions to be composed are called.
+"""
+from functools import reduce
+
+def compose(*functions):
+ """Compose multiple functions into a single function.
+
+ The utility in this function is not specific to this module, and as such,
+ this function can, and probably should, be moved to a more global module.
+
+ DESCRIPTION:
+ Given `cfn = compose(f_1, f_2, ... f_(n-1), f_n )`, calling
+ `cfn(arg_1, arg_2, ..., arg_m)` should call `f_n` with the arguments passed
+ to `cfn` and the results of that should be passed as arguments to `f_(n-1)`
+ and so on until `f_1` is called with the results of the cumulative calls and
+ that is the result of the entire chain of calls.
+
+ PARAMETERS:
+ functions: a variable argument list of function.
+ """
+ def composed_function(*args, **kwargs):
+ return reduce(
+ lambda res, fn: fn(res),
+ reversed(functions[:-1]),
+ functions[-1](*args, **kwargs))
+ return composed_function