Skip to main content

unread() for streams, unnext() for iterators

Project description

Two decorators add_unread and add_unnext for file-like objects and iterators, respectively. add_unread introduces a function unread() for pushing data obtained by read() or readline() back into the input stream. add_unnext introduces a function unnext() for pushing an item back into an iterator (to be returned by the next __next__())

add_unread will work for all kinds of streams: memory-based or file-based, binary or text, buffered or unbuffered. It will also work with higher level operations if those are properly built on top of read() or readline() and also allows to insert content not previously read, because the actual stream is never modified (only a pushback buffer added).

import io
from unread_decorator import add_unread

f = io.StringIO("one\ntwo\nthree")  # or: f = open("myfile.txt")
f = add_unread(f)  # decorate
data = f.readline()  # 'one\n'
data = f.readline()  # 'two\n'
f.unread(data)
data = f.readline()  # 'two\n'
f.unread(data)
f.unread("more than ")
print(f.read())  # prints "more than two\nthree"

add_unnext will work for all kinds of iterators as well as iterables. It is useful if you want to forward some part of an interation to a separate function based on what you encountered. It also allows to insert content not previously received from the iterator.

from unread_decorator import add_unnext

items = add_unnext([11, 12, 13])
results = []
for item in items:
    results.append(item)
    if len(results) == 2:
        items.unnext(item)
        items.unnext(77)
assert results == [11, 12, 77, 12, 13]

Find the documentation at https://github.com/prechelt/unread-decorator

Project details


Release history Release notifications

This version
History Node

1.0

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
unread-decorator-1.0.zip (7.4 kB) Copy SHA256 hash SHA256 Source None

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN SignalFx SignalFx Supporter DigiCert DigiCert EV certificate StatusPage StatusPage Status page