pyflyby 1.8.8

Installation

$ pip install pyflyby

This creates an alias for your ipython named py which runs the pyflyby plug internally.

pyflyby has a dependency on ipython, if it isn’t already installed do install it with:

$ pip install ipython

Quick start: Autoimporter + IPython

$ py
In [1]: re.search("[a-z]+", "....hello...").group(0)
[PYFLYBY] import re
Out[1]: 'hello'

In [2]: chisqprob(arange(5), 2)
[PYFLYBY] from numpy import arange
[PYFLYBY] from scipy.stats import chisqprob
Out[2]: [ 1.      0.6065  0.3679  0.2231  0.1353]

To load pyflyby into an existing IPython session as a 1-off:

$ ipython
In [1]: %load_ext pyflyby

To configure IPython/Jupyter Notebook to load pyflyby automatically:

$ py pyflyby.install_in_ipython_config_file

or

$ echo 'c.InteractiveShellApp.extensions.append("pyflyby")' \
  >> ~/.ipython/profile_default/ipython_config.py

$ ipython
In [1]: b64decode('aGVsbG8=')
[PYFLYBY] from base64 import b64decode
Out[1]: 'hello'

Quick start: py command-line multi-tool

$ py b64decode aGVsbG8=
[PYFLYBY] from base64 import b64decode
[PYFLYBY] b64decode('aGVsbG8=', altchars=None)
'hello'

$ py log2 sys.maxint
[PYFLYBY] from numpy import log2
[PYFLYBY] import sys
[PYFLYBY] log2(9223372036854775807)
63.0

$ py 'plot(cos(arange(30)))'
[PYFLYBY] from numpy import arange
[PYFLYBY] from numpy import cos
[PYFLYBY] from matplotlib.pyplot import plot
[PYFLYBY] plot(cos(arange(30)))
<plot>

$ py 38497631 / 13951446
2.7594007818257693

$ py foo.py

Quick start: tidy-imports

To use tidy-imports, just specify the filename(s) to tidy.

For example:

$ echo 're.search("[a-z]+", "....hello..."), chisqprob(arange(5), 2)' > foo.py

$ tidy-imports foo.py
--- /tmp/foo.py
+++ /tmp/foo.py
@@ -1 +1,9 @@
+from __future__ import absolute_import, division, with_statement
+
+from   numpy                    import arange
+from   scipy.stats              import chisqprob
+import re
+
 re.search("[a-z]+", "....hello..."), chisqprob(arange(5), 2)

Replace /tmp/foo.py? [y/N]

Quick start: import libraries

Create a file named .pyflyby with lines such as

from mypackage.mymodule import MyClass, my_function
import anotherpackage.anothermodule

You can put this file in your home directory or in the same directory as your *.py files.

Details: automatic imports

AUTOMATIC IMPORTS - never type “import” again!

This module allows your “known imports” to work automatically in your IPython interactive session without having to type the ‘import’ statements (and also without having to slow down your Python startup with imports you only use occasionally).

Example:

In [1]: re.search("[a-z]+", "....hello...").group(0)
[PYFLYBY] import re
Out[1]: 'hello'

In [2]: chisqprob(arange(5), 2)
[PYFLYBY] from numpy import arange
[PYFLYBY] from scipy.stats import chisqprob
Out[2]: [ 1.      0.6065  0.3679  0.2231  0.1353]

In [3]: np.sin(arandom(5))
[PYFLYBY] from numpy.random import random as arandom
[PYFLYBY] import numpy as np
Out[3]: [ 0.0282  0.0603  0.4653  0.8371  0.3347]

In [4]: isinstance(42, Number)
[PYFLYBY] from numbers import Number
Out[4]: True

$ ipython
In [1]: nump<TAB>
In [1]: numpy
In [1]: numpy.arang<TAB>
[PYFLYBY] import numpy
In [1]: numpy.arange

$ ipython
In [1]: arange?
[PYFLYBY] from numpy import arange
... Docstring: arange([start,] stop[, step,], dtype=None) ...

$ ipython
In [1]: %timeit np.cos(pi)
[PYFLYBY] import numpy as np
[PYFLYBY] from numpy import pi
100000 loops, best of 3: 2.51 us per loop

$ echo 'print arange(4)' > foo.py
$ ipython
In [1]: %run foo.py
[PYFLYBY] from numpy import arange
[0 1 2 3]

Details: import libraries

Pyflyby uses “import libraries” that tell how to import a given symbol.

An import library file is simply a python source file containing ‘import’ (or ‘from … import …’) lines. These can be generated automatically with collect-imports and collect-exports.

from numpy import arange, NaN

print(arange(10))

PYFLYBY_PATH=/etc/pyflyby:~/.pyflyby:.../.pyflyby

PYFLYBY_PATH=/foo1/bar1:/foo2/bar2

PYFLYBY_PATH=/foo1/bar1:-:/foo2/bar2

/etc/pyflyby/stuff.py
/u/quarl/.pyflyby/blah1.py
/u/quarl/.pyflyby/more/blah2.py
/proj/share/mypythonstuff/.pyflyby
/proj/share/mypythonstuff/foo/bar/.pyflyby/baz.py
/.pyflyby

/etc/pyflyby/stuff.py
/u/quarl/.pyflyby/blah1.py
/u/quarl/.pyflyby/more/blah2.py
/proj/share/mypythonstuff/foo/bar/.pyflyby/baz.py
/proj/share/mypythonstuff/.pyflyby (a file)

__forget_imports__ = ["from numpy import NaN"]

__mandatory_imports__ = ["from __future__ import division"]

__canonical_imports__ = {"oldmodule.oldfunction": "newmodule.newfunction"}

tidy-imports --transform=oldmodule.oldfunction=newmodule.newfunction

Soapbox: avoid “star” imports

When programming in Python, a good software engineering practice is to avoid using from foopackage import * in production code.

This style is a maintenance nightmare:

• It becomes difficult to figure out where various symbols (functions/classes/etc) come from.

• It’s hard to tell what gets shadowed by what.

• When the package changes in trivial ways, your code will be affected. Consider the following example: Suppose foopackage.py contains import sys, and myprogram.py contains from foopackage import *; if some_condition: sys.exit(0). If foopackage.py changes so that import sys is removed, myprogram.py is now broken because it’s missing import sys.

To fix such code, you can run tidy-imports --replace-star-imports to automatically replace star imports with the specific needed imports.

Per-Project configuration of tidy-imports

You can configure Pyflyby on a per-repository basis by using the [tool.pyflyby] section of pyproject.toml files. Pyflyby will look in current working directory and all it’s parent until it find a pyproject.toml file from which it will load the defaults.

Most of the long command line flags default values can be configured in this section. Simply use the long form option name by replacing dashes - by underscore _. For long option that have the form –xxx and –no-xxx, you can assign a boolean to xxx. For example:

[tool.pyflyby]
add_missing=true
from_spaces=7
remove_unused=false

Emacs support

• To get a M-x tidy-imports command in GNU Emacs, add to your ~/.emacs:

  (load "/path/to/pyflyby/lib/emacs/pyflyby.el")

• Pyflyby.el doesn’t yet work with XEmacs; patches welcome.

Authorship

This plugin was contributed back to the community by the D. E. Shaw group.

Pyflyby is written by Karl Chen <quarl@8166.clguba.z.quarl.org>

We love contributions! Before you can contribute, please sign and submit this Contributor License Agreement (CLA). This CLA is in place to protect all users of this project.

License

Pyflyby is released under a very permissive license, the MIT/X11 license; see LICENSE.txt.

Release

1. Check version number in lib/python/pyflyby/_version.py, maybe increase it.

2. Commit and tag if necessary, and push tags/commits.

3. Optional: Set SOURCE_DATE_EPOCH for reproducible build:

   export SOURCE_DATE_EPOCH=$(git show -s --format=%ct HEAD)

4. Build the SDIST:

   python setup.py sdist

5. Optional Repack the Sdist to make sure the ZIP only contain SOURCE_DATE_EPOCH date using IPython tools:

   python ~/dev/ipython/tools/retar.py dist/pyflyby-1.7.8.tar.gz
   shasum -a 256 dist/*

6. Optional, redo 4 & 5 to verify checksum is unchanged.

7. Upload using twine:

   twine upload dist/*

8. Check/update https://github.com/conda-forge/pyflyby-feedstock for new pyflyby release on conda-forge