pfa 0.4

# PFA (Python Fast Autoformat)

An autoformatter should be three things:

• Fast: Run quickly so that you can afford to run the autoformatter on a large code base without ever having to wait for the autoformat to complete.

• Consistent: Running the autoformatter a second time won’t change the output. Code will run the same before and after the autoformatter is run. Trivial whitespace changes will be reverted.

• Pretty: Output looks nice and preferably follows PEP8.

PFA chooses to be Fast and Consistent, but sacrifices Pretty output in favor of speed.

## Installation and Usage

To create the executable file pfa, run

make

Afterwards you can copy it into PATH, say to /usr/bin or ~/bin/.

There are two ways to run the program. If the executable file name does not end in “i”, i.e. with

pfa that_python_script.py

then the formatted file will be dumped to standard output. If you make a symlink from pfa to pfai and run the latter like

pfai that_python_script.py scriptus_secundus.py

then all files listed as arguments will be formatted in place.

## FAQ

• Why is PFA written in C? The startup time for the Python interpreter is often longer than it takes to run pfa on a 2000 line file.

• How fast is it? The other popular Python formatters are yapf and autopep8. Formatting about 120KB of python code in place for the second time in a row with the following commands,

  yapf -i bx.py autopep8 -i bx.py pfai bx.py

  one finds that yapf takes 14.0 seconds; autopep8 takes 1.8 seconds; and pfai completes in 0.020 seconds, less than the time it takes to press Enter.

• I have a change to contribute. Will it be accepted?: Yes, as long as pfa still runs in O(n) for even pathological input.