Install from PyPI:
$ pipenv install vistir
Install from Github:
$ pipenv install -e git+https://github.com/sarugaku/vistir.git#egg=vistir
vistir is a library full of utility functions designed to make life easier. Here are some of the places where these functions are used:
You can import utilities directly from vistir:
from vistir import cd
with cd('/path/to/somedir'):
do_stuff_in('somedir')vistir provides several categories of functionality, including:
- Compatibility Shims
- Context Managers
- Miscellaneous Utilities
- Path Utilities
vistir provides the following context managers as utility contexts:
vistir.contextmanagers.atomic_open_for_writevistir.contextmanagers.cdvistir.contextmanagers.open_filevistir.contextmanagers.replaced_streamvistir.contextmanagers.replaced_streamsvistir.contextmanagers.temp_environvistir.contextmanagers.temp_path
This context manager ensures that a file only gets overwritten if the contents can be successfully written in its place. If you open a file for writing and then fail in the middle under normal circumstances, your original file is already gone.
>>> fn = "test_file.txt"
>>> with open(fn, "w") as fh:
fh.write("this is some test text")
>>> read_test_file()
this is some test text
>>> def raise_exception_while_writing(filename):
with vistir.contextmanagers.atomic_open_for_write(filename) as fh:
fh.write("Overwriting all the text from before with even newer text")
raise RuntimeError("But did it get overwritten now?")
>>> raise_exception_while_writing(fn)
Traceback (most recent call last):
...
RuntimeError: But did it get overwritten now?
>>> read_test_file()
this is some test textA context manager for temporarily changing the working directory.
>>> os.path.abspath(os.curdir)
'/tmp/test'
>>> with vistir.contextmanagers.cd('/tmp/vistir_test'):
print(os.path.abspath(os.curdir))
/tmp/vistir_testA context manager for streaming file contents, either local or remote. It is recommended to pair this with an iterator which employs a sensible chunk size.
>>> filecontents = b""
with vistir.contextmanagers.open_file("https://norvig.com/big.txt") as fp:
for chunk in iter(lambda: fp.read(16384), b""):
filecontents.append(chunk)
>>> import io
>>> import shutil
>>> filecontents = io.BytesIO(b"")
>>> with vistir.contextmanagers.open_file("https://norvig.com/big.txt") as fp:
shutil.copyfileobj(fp, filecontents)A context manager to temporarily swap out stream_name with a stream wrapper. This will capture the stream output and prevent it from being written as normal.
>>> orig_stdout = sys.stdout
>>> with replaced_stream("stdout") as stdout:
... sys.stdout.write("hello")
... assert stdout.getvalue() == "hello"
... assert orig_stdout.getvalue() != "hello"
>>> sys.stdout.write("hello")
'hello'Temporarily replaces both sys.stdout and sys.stderr and captures anything written to these respective targets.
>>> import sys
>>> with vistir.contextmanagers.replaced_streams() as streams:
>>> stdout, stderr = streams
>>> sys.stderr.write("test")
>>> sys.stdout.write("hello")
>>> assert stdout.getvalue() == "hello"
>>> assert stderr.getvalue() == "test"
>>> stdout.getvalue()
'hello'
>>> stderr.getvalue()
'test'A context manager for wrapping some actions with a threaded, interrupt-safe spinner. The
spinner is fully compatible with all terminals (you can use bouncingBar on non-utf8
terminals) and will allow you to update the text of the spinner itself by simply setting
spinner.text or write lines to the screen above the spinner by using
spinner.write(line). Success text can be indicated using spinner.ok("Text") and
failure text can be indicated with spinner.fail("Fail text").
>>> lines = ["a", "b"]
>>> with vistir.contextmanagers.spinner(spinner_name="dots", text="Running...", handler_map={}, nospin=False) as sp:
for line in lines:
sp.write(line + "\n")
while some_variable = some_queue.pop():
sp.text = "Consuming item: %s" % some_variable
if success_condition:
sp.ok("Succeeded!")
else:
sp.fail("Failed!")Sets a temporary environment context to freely manipulate os.environ which will
be reset upon exiting the context.
>>> os.environ['MY_KEY'] = "test"
>>> os.environ['MY_KEY']
'test'
>>> with vistir.contextmanagers.temp_environ():
os.environ['MY_KEY'] = "another thing"
print("New key: %s" % os.environ['MY_KEY'])
New key: another thing
>>> os.environ['MY_KEY']
'test'Sets a temporary environment context to freely manipulate sys.path which will
be reset upon exiting the context.
>>> path_from_virtualenv = load_path("/path/to/venv/bin/python")
>>> print(sys.path)
['/home/user/.pyenv/versions/3.7.0/bin', '/home/user/.pyenv/versions/3.7.0/lib/python37.zip', '/home/user/.pyenv/versions/3.7.0/lib/python3.7', '/home/user/.pyenv/versions/3.7.0/lib/python3.7/lib-dynload', '/home/user/.pyenv/versions/3.7.0/lib/python3.7/site-packages']
>>> with temp_path():
sys.path = path_from_virtualenv
# Running in the context of the path above
run(["pip", "install", "stuff"])
>>> print(sys.path)
['/home/user/.pyenv/versions/3.7.0/bin', '/home/user/.pyenv/versions/3.7.0/lib/python37.zip', '/home/user/.pyenv/versions/3.7.0/lib/python3.7', '/home/user/.pyenv/versions/3.7.0/lib/python3.7/lib-dynload', '/home/user/.pyenv/versions/3.7.0/lib/python3.7/site-packages']The following Cursor utilities are available to manipulate the console cursor:
vistir.cursor.hide_cursorvistir.cursor.show_cursor
Hide the console cursor in the given stream.
>>> vistir.cursor.hide_cursor(stream=sys.stdout)Show the console cursor in the given stream.
>>> vistir.cursor.show_cursor(stream=sys.stdout)The following Miscellaneous utilities are available as helper methods:
vistir.misc.shell_escapevistir.misc.unnestvistir.misc.runvistir.misc.load_pathvistir.misc.partialclassvistir.misc.to_textvistir.misc.to_bytesvistir.misc.takevistir.misc.decode_for_outputvistir.misc.get_canonical_encoding_namevistir.misc.get_wrapped_streamvistir.misc.StreamWrappervistir.misc.get_text_streamvistir.misc.replace_with_text_streamvistir.misc.get_text_stdinvistir.misc.get_text_stdoutvistir.misc.get_text_stderrvistir.misc.echo
Escapes a string for use as shell input when passing shell=True to os.Popen.
>>> vistir.misc.shell_escape("/tmp/test/test script.py hello")
'/tmp/test/test script.py hello'Unnests nested iterables into a flattened one.
>>> nested_iterable = (1234, (3456, 4398345, (234234)), (2396, (23895750, 9283798, 29384, (289375983275, 293759, 2347, (2098, 7987, 27599)))))
>>> list(vistir.misc.unnest(nested_iterable))
[1234, 3456, 4398345, 234234, 2396, 23895750, 9283798, 29384, 289375983275, 293759, 2347, 2098, 7987, 27599]Deduplicates an iterable (like a set, but preserving order).
>>> iterable = ["repeatedval", "uniqueval", "repeatedval", "anotherval", "somethingelse"]
>>> list(vistir.misc.dedup(iterable))
['repeatedval', 'uniqueval', 'anotherval', 'somethingelse']Runs the given command using subprocess.Popen and passing sane defaults.
>>> out, err = vistir.run(["cat", "/proc/version"])
>>> out
'Linux version 4.15.0-27-generic (buildd@lgw01-amd64-044) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #29-Ubuntu SMP Wed Jul 11 08:21:57 UTC 2018'Load the sys.path from the given python executable's environment as json.
>>> load_path("/home/user/.virtualenvs/requirementslib-5MhGuG3C/bin/python")
['', '/home/user/.virtualenvs/requirementslib-5MhGuG3C/lib/python37.zip', '/home/user/.virtualenvs/requirementslib-5MhGuG3C/lib/python3.7', '/home/user/.virtualenvs/requirementslib-5MhGuG3C/lib/python3.7/lib-dynload', '/home/user/.pyenv/versions/3.7.0/lib/python3.7', '/home/user/.virtualenvs/requirementslib-5MhGuG3C/lib/python3.7/site-packages', '/home/user/git/requirementslib/src']Create a partially instantiated class.
>>> source = partialclass(Source, url="https://pypi.org/simple")
>>> new_source = source(name="pypi")
>>> new_source
<__main__.Source object at 0x7f23af189b38>
>>> new_source.__dict__
{'url': 'https://pypi.org/simple', 'verify_ssl': True, 'name': 'pypi'}Convert arbitrary text-formattable input to text while handling errors.
>>> vistir.misc.to_text(b"these are bytes")
'these are bytes'Converts arbitrary byte-convertable input to bytes while handling errors.
>>> vistir.misc.to_bytes("this is some text")
b'this is some text'
>>> vistir.misc.to_bytes(u"this is some text")
b'this is some text'Splits an iterable up into groups of the specified length, per more itertools. Returns an iterable.
This example will create groups of chunk size 5, which means there will be 6 groups.
>>> chunked_iterable = vistir.misc.chunked(5, range(30))
>>> for chunk in chunked_iterable:
... add_to_some_queue(chunk)Take elements from the supplied iterable without consuming it.
>>> iterable = range(30)
>>> first_10 = take(10, iterable)
>>> [i for i in first_10]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> [i for i in iterable]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]Splits an iterable up into the specified number of groups, per more itertools. Returns an iterable.
>>> iterable = range(30)
>>> groups = []
>>> for grp in vistir.misc.divide(3, iterable):
... groups.append(grp)
>>> groups
[<tuple_iterator object at 0x7fb7966006a0>, <tuple_iterator object at 0x7fb796652780>, <tuple_iterator object at 0x7fb79650a2b0>]Converts an arbitrary text input to output which is encoded for printing to terminal
outputs using the system preferred locale using locale.getpreferredencoding(False)
with some additional hackery on linux systems.
Given an encoding name, get the canonical name from a codec lookup.
>>> vistir.misc.get_canonical_encoding_name("utf8")
"utf-8"Given a stream, wrap it in a StreamWrapper instance and return the wrapped stream.
>>> stream = sys.stdout
>>> wrapped_stream = vistir.misc.get_wrapped_stream(sys.stdout)
>>> wrapped_stream.write("unicode\u0141")
>>> wrapped_stream.seek(0)
>>> wrapped_stream.read()
"unicode\u0141"A stream wrapper and compatibility class for handling wrapping file-like stream objects
which may be used in place of sys.stdout and other streams.
>>> wrapped_stream = vistir.misc.StreamWrapper(sys.stdout, encoding="utf-8", errors="replace", line_buffering=True)
>>> wrapped_stream = vistir.misc.StreamWrapper(io.StringIO(), encoding="utf-8", errors="replace", line_buffering=True)An implementation of the StreamWrapper for the purpose of wrapping sys.stdin or sys.stdout.
On Windows, this returns the appropriate handle to the requested output stream.
>>> text_stream = vistir.misc.get_text_stream("stdout")
>>> sys.stdout = text_stream
>>> sys.stdin = vistir.misc.get_text_stream("stdin")
>>> vistir.misc.echo(u"\0499", fg="green")
ҙGiven a text stream name, replaces the text stream with a StreamWrapper instance.
>>> vistir.misc.replace_with_text_stream("stdout")Once invoked, the standard stream in question is replaced with the required wrapper,
turning it into a TextIOWrapper compatible stream (which ensures that unicode
characters can be written to it).
A helper function for calling get_text_stream("stdin").
A helper function for calling get_text_stream("stdout").
A helper function for calling get_text_stream("stderr").
Writes colored, stream-compatible output to the desired handle (sys.stdout by default).
>>> vistir.misc.echo("some text", fg="green", bg="black", style="bold", err=True) # write to stderr
some text
>>> vistir.misc.echo("some other text", fg="cyan", bg="white", style="underline") # write to stdout
some other textvistir provides utilities for interacting with filesystem paths:
vistir.path.get_converted_relative_pathvistir.path.normalize_pathvistir.path.is_in_pathvistir.path.handle_remove_readonlyvistir.path.is_file_urlvistir.path.is_readonly_pathvistir.path.is_valid_urlvistir.path.mkdir_pvistir.path.ensure_mkdir_pvistir.path.create_tracked_tempdirvistir.path.create_tracked_tempfilevistir.path.path_to_urlvistir.path.rmtreevistir.path.safe_expandvarsvistir.path.set_write_bitvistir.path.url_to_pathvistir.path.walk_up
Return a case-normalized absolute variable-expanded path.
>>> vistir.path.normalize_path("~/${USER}")
/home/user/userDetermine if the provided full path is in the given parent root.
>>> vistir.path.is_in_path("~/.pyenv/versions/3.7.1/bin/python", "${PYENV_ROOT}/versions")
TrueConvert the supplied path to a relative path (relative to os.curdir)
>>> os.chdir('/home/user/code/myrepo/myfolder')
>>> vistir.path.get_converted_relative_path('/home/user/code/file.zip')
'./../../file.zip'
>>> vistir.path.get_converted_relative_path('/home/user/code/myrepo/myfolder/mysubfolder')
'./mysubfolder'
>>> vistir.path.get_converted_relative_path('/home/user/code/myrepo/myfolder')
'.'Error handler for shutil.rmtree.
Windows source repo folders are read-only by default, so this error handler attempts to set them as writeable and then proceed with deletion.
This function will call check vistir.path.is_readonly_path before attempting to
call vistir.path.set_write_bit on the target path and try again.
Checks whether the given url is a properly formatted file:// uri.
>>> vistir.path.is_file_url('file:///home/user/somefile.zip')
True
>>> vistir.path.is_file_url('/home/user/somefile.zip')
FalseCheck if a provided path exists and is readonly by checking for bool(path.stat & stat.S_IREAD) and not os.access(path, os.W_OK)
>>> vistir.path.is_readonly_path('/etc/passwd')
True
>>> vistir.path.is_readonly_path('/home/user/.bashrc')
FalseChecks whether a URL is valid and parseable by checking for the presence of a scheme and a netloc.
>>> vistir.path.is_valid_url("https://google.com")
True
>>> vistir.path.is_valid_url("/home/user/somefile")
FalseRecursively creates the target directory and all of its parents if they do not already exist. Fails silently if they do.
>>> os.mkdir('/tmp/test_dir')
>>> os.listdir('/tmp/test_dir')
[]
>>> vistir.path.mkdir_p('/tmp/test_dir/child/subchild/subsubchild')
>>> os.listdir('/tmp/test_dir/child/subchild')
['subsubchild']A decorator which ensures that the caller function's return value is created as a directory on the filesystem.
>>> @ensure_mkdir_p
def return_fake_value(path):
return path
>>> return_fake_value('/tmp/test_dir')
>>> os.listdir('/tmp/test_dir')
[]
>>> return_fake_value('/tmp/test_dir/child/subchild/subsubchild')
>>> os.listdir('/tmp/test_dir/child/subchild')
['subsubchild']Creates a tracked temporary directory using vistir.path.TemporaryDirectory, but does
not remove the directory when the return value goes out of scope, instead registers a
handler to cleanup on program exit.
>>> temp_dir = vistir.path.create_tracked_tempdir(prefix="test_dir")
>>> assert temp_dir.startswith("test_dir")
True
>>> with vistir.path.create_tracked_tempdir(prefix="test_dir") as temp_dir:
with io.open(os.path.join(temp_dir, "test_file.txt"), "w") as fh:
fh.write("this is a test")
>>> os.listdir(temp_dir)Creates a tracked temporary file using vistir.compat.NamedTemporaryFile, but creates
a weakref.finalize call which will detach on garbage collection to close and delete
the file.
>>> temp_file = vistir.path.create_tracked_tempfile(prefix="requirements", suffix="txt")
>>> temp_file.write("some\nstuff")
>>> exit()Convert the supplied local path to a file uri.
>>> path_to_url("/home/user/code/myrepo/myfile.zip")
'file:///home/user/code/myrepo/myfile.zip'Stand-in for shutil.rmtree with additional error-handling.
This version of rmtree handles read-only paths, especially in the case of index files written by certain source control systems.
>>> vistir.path.rmtree('/tmp/test_dir')
>>> [d for d in os.listdir('/tmp') if 'test_dir' in d]
[]Note
Setting ignore_errors=True may cause this to silently fail to delete the path
Call os.path.expandvars if value is a string, otherwise do nothing.
>>> os.environ['TEST_VAR'] = "MY_TEST_VALUE"
>>> vistir.path.safe_expandvars("https://myuser:${TEST_VAR}@myfakewebsite.com")
'https://myuser:MY_TEST_VALUE@myfakewebsite.com'Set read-write permissions for the current user on the target path. Fail silently if the path doesn't exist.
>>> vistir.path.set_write_bit('/path/to/some/file')
>>> with open('/path/to/some/file', 'w') as fh:
fh.write("test text!")Convert a valid file url to a local filesystem path. Follows logic taken from pip.
>>> vistir.path.url_to_path("file:///home/user/somefile.zip")
'/home/user/somefile.zip'