py.io

The ‘py’ lib provides helper classes for capturing IO during execution of a program.

IO Capturing examples

py.io.StdCapture

Basic Example:

>>> import py
>>> capture = py.io.StdCapture()
>>> print "hello"
>>> out,err = capture.reset()
>>> out.strip() == "hello"
True

For calling functions you may use a shortcut:

>>> import py
>>> def f(): print "hello"
>>> res, out, err = py.io.StdCapture.call(f)
>>> out.strip() == "hello"
True

py.io.StdCaptureFD

If you also want to capture writes to the stdout/stderr filedescriptors you may invoke:

>>> import py, sys
>>> capture = py.io.StdCaptureFD(out=False, in_=False)
>>> sys.stderr.write("world")
>>> out,err = capture.reset()
>>> err
'world'

py.io object reference

class py.io.StdCaptureFD(out=True, err=True, mixed=False, in_=True, patchsys=True, now=True)

This class allows to capture writes to FD1 and FD2 and may connect a NULL file to FD0 (and prevent reads from sys.stdin). If any of the 0,1,2 file descriptors is invalid it will not be captured.

resume()

resume capturing with original temp files.

done(save=True)

return (outfile, errfile) and stop capturing.

readouterr()

return snapshot value of stdout/stderr capturings.

classmethod call(func, *args, **kwargs)

return a (res, out, err) tuple where out and err represent the output/error output during function execution. call the given function with args/kwargs and capture output/error during its execution.

reset()

reset sys.stdout/stderr and return captured output as strings.

suspend()

return current snapshot captures, memorize tempfiles.

class py.io.StdCapture(out=True, err=True, in_=True, mixed=False, now=True)

This class allows to capture writes to sys.stdout|stderr “in-memory” and will raise errors on tries to read from sys.stdin. It only modifies sys.stdout|stderr|stdin attributes and does not touch underlying File Descriptors (use StdCaptureFD for that).

done(save=True)

return (outfile, errfile) and stop capturing.

resume()

resume capturing with original temp files.

readouterr()

return snapshot value of stdout/stderr capturings.

classmethod call(func, *args, **kwargs)

return a (res, out, err) tuple where out and err represent the output/error output during function execution. call the given function with args/kwargs and capture output/error during its execution.

reset()

reset sys.stdout/stderr and return captured output as strings.

suspend()

return current snapshot captures, memorize tempfiles.

class py.io.TerminalWriter(file=None, stringio=False, encoding=None)

chars_on_current_line

Return the number of characters written so far in the current line.

Please note that this count does not produce correct results after a reline() call, see #164.

New in version 1.5.0.

Return type:int

width_of_current_line

Return an estimate of the width so far in the current line.

New in version 1.6.0.

Return type:int