PyPI 官网下载 | chainz-0.11.tar.gz

Chainz ====== Chainz is a lightweight library to provide chaining, functional methods to iterables. To install: `pip install chainz` Basic example: ```python from chainz import Chain Chain(xrange(10))\ .map(lambda x: x + 1)\ .filter(lambda x: x % 2 == 0)\ .omit(lambda x: x % 3 == 0)\ .reduce(lambda x, y: x + y) # 30 ``` Chain ----- The fundamental class in `chainz` is `Chain`, which accepts an iterable as an argument to its constructor. It is itself an iterable, just exposing the supplied iterable. It exposes functional methods like `map`, `filter`, and `flatten`, which return the chain so as to be chainable. These methods alter the chain; `chain.map(f)` is the same as `chain = chain.map(f)`. Some methods, such as `reduce` and `for_each`, are "sinks", in that they consume the iterable. These methods do not return the chain, to make it clear that once they are called, the chain is done. All non-sink methods are lazy, so they don't result in any evaluation. Only by using a sink method, or consuming the iterable in another way (such as `list(chain)` or `[x for x in chain]`), do you actually evaluate the iterable. You can think of `Chain` as a way to wrap `itertools` in a more chainable fashion. Errors ------ By default, a `Chain` will stop whenever there's an exception. Often that is not what you want. When you are processing a long list of items (something for which `Chain` was specifically created for), you just want to note what went wrong, and move on to the next item. The method `on_error` allows just that. It takes a function `f(exception, object)` which itself takes two parameter. The first parameter is the raised exception. The second parameter is the object that caused the exception. #### Example ```python def on_error(exception, obj): print("%s caused exception: %s" % (exception, obj)) def double(x): if x == 1: raise Exception('Bad') return x*2 chain = Chain(xrange(3)).on_error(on_error).map(double) list(chain) # "1 caused exception: Exception('Bad')" # [0, 2] ``` API --- Please see the `docs/` directory for auto-generated (and thus up-to-date) documentation. This is generated from the doc strings, so introspection can also be helpful (eg, `print Chain.reduce.__doc__`).