wrapperutils.py 20.6 KB
Newer Older
1
2
#!/usr/bin/env python
#
Paul McCarthy's avatar
Paul McCarthy committed
3
4
# wrapperutils.py - Functions and decorators used by the FSL wrapper
# functions.
5
6
7
#
# Author: Paul McCarthy <pauldmccarthy@gmail.com>
#
Paul McCarthy's avatar
Paul McCarthy committed
8
9
10
11
12
13
14
15
16
17
18
"""This module contains functions and decorators used by the FSL wrapper
functions.

.. autosummary::
   :nosignatures:

   applyArgStyle
   required
   fileOrImage
   fileOrArray
"""
19
20
21
22


import os.path as op
import            os
Paul McCarthy's avatar
Paul McCarthy committed
23
import            sys
24
25
26
27
28
29
30
31
import            inspect
import            tempfile
import            warnings
import            functools
import            collections

import            six
import nibabel as nib
Paul McCarthy's avatar
Paul McCarthy committed
32
import numpy   as np
33
34
35
36
37

import fsl.utils.tempdir as tempdir
import fsl.data.image    as fslimage


Paul McCarthy's avatar
Paul McCarthy committed
38
39
40
41
42
43
44
45
46
47
48
def _update_wrapper(wrapper, wrapped, *args, **kwargs):
    """Replacement for the built-in ``functools.update_wrapper``. This
    implementation ensures that the wrapper function has an attribute
    called ``__wrapped__``, which refers to the ``wrapped`` function.

    This behaviour is only required in Python versions < 3.4.
    """

    wrapper = functools.update_wrapper(wrapper, wrapped, *args, **kwargs)

    # Python >= 3.4 does things right
Paul McCarthy's avatar
Paul McCarthy committed
49
    if (sys.version_info[0] * 10 + sys.version_info[1]) < 34:
Paul McCarthy's avatar
Paul McCarthy committed
50
51
        wrapper.__wrapped__ = wrapped
    return wrapper
52
53


Paul McCarthy's avatar
Paul McCarthy committed
54
55
56
57
58
59
def _unwrap(func):
    """Replacement for the built-in ``inspect.unwrap`` function, which
    is not present in Python versions prior to 3.4.
    """

    # Python >= 3.4 has an inspect.unwrap function
Paul McCarthy's avatar
Paul McCarthy committed
60
    if (sys.version_info[0] * 10 + sys.version_info[1]) >= 34:
Paul McCarthy's avatar
Paul McCarthy committed
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
        return inspect.unwrap(func)

    # Otherwise we follow the __wrapped__ chain ourselves
    if hasattr(func, '__wrapped__'):
        return _unwrap(func.__wrapped__)

    return func


SHOW_IF_TRUE = object()
"""Constant to be used in the ``valmap`` passed to the :func:`applyArgStyle`
function.

When a ``SHOW_IF_TRUE`` argument is ``True``, it is added to the generated
command line arguments.
"""


HIDE_IF_TRUE = object()
"""Constant to be used in the ``valmap`` passed to the :func:`applyArgStyle`
function.

When a ``HIDE_IF_TRUE`` argument is ``True``, it is suppressed from the
generated command line arguments.
"""
86
87


88
def applyArgStyle(style, valsep=None, argmap=None, valmap=None, **kwargs):
Paul McCarthy's avatar
Paul McCarthy committed
89
90
91
92
    """Turns the given ``kwargs`` into command line options. This function
    is intended to be used to automatically generate command line options
    from arguments passed into a Python function.

93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
    The ``style`` and ``valsep`` arguments control how key-value pairs
    are converted into command-line options:


    =========  ==========  ===========================
    ``style``  ``valsep``  Result
    =========  ==========  ===========================
    ``'-'``    ' '         ``-name val1 val2 val3``
    ``'-'``    '"'         ``-name "val1 val2 val3"``
    ``'-'``    ','         ``-name val1,val2,val3``
    ``'--'``   ' '         ``--name val1 val2 val3``
    ``'--'``   '"'         ``--name "val1 val2 val3"``
    ``'--'``   ','         ``--name val1,val2,val3``
    ``'-='``   ' '         Not supported
    ``'-='``   '"'         ``-name="val1 val2 val3"``
    ``'-='``   ','         ``-name=val1,val2,val3``
    ``'--='``  ' '         Not supported
    ``'--='``  '"'         ``--name="val1 val2 val3"``
    ``'--='``  ','         ``--name=val1,val2,val3``
    =========  ==========  ===========================


Paul McCarthy's avatar
Paul McCarthy committed
115
    :arg style:  Controls how the ``kwargs`` are converted into command-line
116
117
118
119
120
                 options - must be one of ``'-'``, ``'--'``, ``'-='``, or
                 ``'--='``.

    :arg valsep: Controls how the values passed to command-line options
                 which expect multiple arguments are delimited - must be
121
122
                 one of ``' '``, ``','`` or ``'"'``. Defaults to ``' '``
                 if ``'=' not in style``, ``','`` otherwise.
Paul McCarthy's avatar
Paul McCarthy committed
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145

    :arg argmap: Dictionary of ``{kwarg-name : cli-name}`` mappings. This can
                 be used if you want to use different argument names in your
                 Python function for the command-line options.

    :arg valmap: Dictionary of ``{cli-name : value}`` mappings. This can be
                 used to define specific semantics for some command-line
                 options. Acceptable values for ``value`` are as follows

                  - :data:`SHOW_IF_TRUE` - if the argument is present, and
                    ``True`` in ``kwargs``, the command line option
                    will be added (without any arguments).

                  - :data:`HIDE_IF_TRUE` - if the argument is present, and
                    ``False`` in ``kwargs``, the command line option
                    will be added (without any arguments).

                  - Any other constant value. If the argument is present
                    in ``kwargs``, its command-line option will be
                    added, with the constant value as its argument.

                 The argument for any options not specified in the ``valmap``
                 will be converted into strings.
146

Paul McCarthy's avatar
Paul McCarthy committed
147
148
149
150
151
    :arg kwargs: Arguments to be converted into command-line options.

    :returns:    A list containing the generated command-line options.
    """

152
153
154
155
    if valsep is None:
        if '=' in style: valsep = ','
        else:            valsep = ' '

Paul McCarthy's avatar
Paul McCarthy committed
156
157
    if style not in ('-', '--', '-=', '--='):
        raise ValueError('Invalid style: {}'.format(style))
158
159
160
161
162
163
164
165
166
    if valsep not in (' ', ',', '"'):
        raise ValueError('Invalid valsep: {}'.format(valsep))

    # we don't handle the case where '=' in
    # style, and valsep == ' ', because no
    # sane CLI app would do this. Right?
    if '=' in style and valsep == ' ':
        raise ValueError('Incompatible style and valsep: s={} v={}'.format(
            style, valsep))
Paul McCarthy's avatar
Paul McCarthy committed
167
168
169
170
171

    if argmap is None: argmap = {}
    if valmap is None: valmap = {}

    def fmtarg(arg):
172
173
174
175
        if   style in ('-',  '-='):  arg =  '-{}'.format(arg)
        elif style in ('--', '--='): arg = '--{}'.format(arg)
        return arg

176
    # always returns a sequence
Paul McCarthy's avatar
Paul McCarthy committed
177
    def fmtval(val):
178
179
        if     isinstance(val, collections.Sequence) and \
           not isinstance(val, six.string_types):
180
181
182
183
184

            val = [str(v) for v in val]
            if   valsep == ' ': return val
            elif valsep == '"': return [' '   .join(val)]
            else:               return [valsep.join(val)]
185
        else:
186
187
188
189
190
191
192
193
            return [str(val)]

    # val is assumed to be a sequence
    def fmtargval(arg, val):
        # if '=' in style, val will
        # always be a single string
        if '=' in style: return ['{}={}'.format(arg, val[0])]
        else:            return [arg] + val
194
195
196
197
198
199

    args = []

    for k, v in kwargs.items():

        k    = argmap.get(k, k)
Paul McCarthy's avatar
Paul McCarthy committed
200
201
202
        mapv = valmap.get(k, fmtval(v))
        k    = fmtarg(k)

203

204
205
206
207
        if mapv in (SHOW_IF_TRUE, HIDE_IF_TRUE):
            if (mapv is SHOW_IF_TRUE and     v) or \
               (mapv is HIDE_IF_TRUE and not v):
                args.append(k)
208
        else:
209
            args.extend(fmtargval(k, mapv))
210
211
212
213
214

    return args


def required(*reqargs):
215
216
217
218
219
220
221
    """Decorator which makes sure that all specified arguments are present
    before calling the decorated function. Arguments which are not present
    will result in an :exc:`AssertionError`. Use as follows::

        @required('foo')
        def funcWhichRequires_foo(**kwargs):
            foo = kwargs['foo']
222
    """
Paul McCarthy's avatar
Paul McCarthy committed
223

224
    def decorator(func):
Paul McCarthy's avatar
Paul McCarthy committed
225
        def wrapper(*args, **kwargs):
226
            argnames = namedPositionals(func, args)
227
            for reqarg in reqargs:
228
                assert (reqarg in kwargs) or (reqarg in argnames)
229
            return func(**kwargs)
230
        return _update_wrapper(wrapper, func)
231
232
233
    return decorator


234
def namedPositionals(func, args):
235
    """Given a function, and a sequence of positional arguments destined
236
237
    for that function, identiifes the name for each positional argument.
    Variable positional arguments are given an automatic name.
238

239
240
    :arg func: Function which will accept ``args`` as positionals.
    :arg args: Tuple of positional arguments to be passed to ``func``.
241
    """
Paul McCarthy's avatar
Paul McCarthy committed
242

243
244
245
246
247
248
249
250
251
252
    # Current implementation will
    # result in naming collisions
    # for something like this:
    #
    # def func(args0, *args):
    #     ...
    # because of automatic vararg
    # naming. But who would write
    # a function like that anyway?

253
254
    # Remove any decorators
    # from the function
Paul McCarthy's avatar
Paul McCarthy committed
255
256
    func = _unwrap(func)

257
258
259
    # getargspec is the only way to
    # get the names of positional
    # arguments in Python 2.x.
Paul McCarthy's avatar
Paul McCarthy committed
260
    if sys.version_info[0] < 3:
261
262
263
        spec     = inspect.getargspec(func)
        argnames = spec.args
        varargs  = spec.varargs
Paul McCarthy's avatar
Paul McCarthy committed
264

265
266
    # But getargspec is deprecated
    # in python 3.x
Paul McCarthy's avatar
Paul McCarthy committed
267
268
269
270
271
272
    else:

        # getfullargspec is deprecated in
        # python 3.5, but not in python 3.6.
        with warnings.catch_warnings():
            warnings.filterwarnings('ignore', category=DeprecationWarning)
273
274
275
            spec     = inspect.getfullargspec(func)
            argnames = spec.args
            varargs  = spec.varargs
276

277
278
279
    # we only care about the arguments
    # that are being passed in
    argnames = argnames[:len(args)]
280

281
282
283
284
    # make up names for varargs
    nvarargs = len(args) - len(argnames)
    if varargs is not None and nvarargs > 0:
        argnames += ['{}{}'.format(varargs, i) for i in range(nvarargs)]
285

286
    return argnames
287
288


Paul McCarthy's avatar
Paul McCarthy committed
289
LOAD = object()
Paul McCarthy's avatar
Paul McCarthy committed
290
291
"""Constant used by the :class:`_FileOrThing` class to indicate that an output
file should be loaded into memory and returned as a Python object.
292
293
294
"""


Paul McCarthy's avatar
Paul McCarthy committed
295
296
297
298
299
300
301
302
303
304
class _FileOrThing(object):
    """Decorator which ensures that certain arguments which are passed into the
    decorated function are always passed as file names. Both positional and
    keyword arguments can be specified.


    The ``_FileOrThing`` class is not intended to be used directly - see the
    :func:`fileOrImage` and :func:`fileOrArray` decorator functions for more
    details.

305

Paul McCarthy's avatar
Paul McCarthy committed
306
307
308
309
310
311
312
313
314
315
316
317
    These decorators are intended for functions which wrap a command-line tool,
    i.e. where some inputs/outputs need to be specified as file names.


    **Inputs**


    Any arguments which are not of type ``Thing`` are passed through to the
    decorated function unmodified.  Arguments which are of type ``Thing`` are
    saved to a temporary file, and the name of that file is passed to the
    function.

318

Paul McCarthy's avatar
Paul McCarthy committed
319
    **Outputs**
320
321


Paul McCarthy's avatar
Paul McCarthy committed
322
    If an argument is given the special :data:`LOAD` value, it is assumed
Paul McCarthy's avatar
Paul McCarthy committed
323
324
325
    to be an output argument. In this case, it is replaced with a temporary
    file name then, after the function has completed, that file is loaded
    into memory, and the value returned (along with the function's output,
Paul McCarthy's avatar
Paul McCarthy committed
326
    and any other arguments with a value of ``LOAD``).
Paul McCarthy's avatar
Paul McCarthy committed
327
328
329
330
331
332


    **Return value**


    Functions decorated with a ``_FileOrThing`` decorator will always return a
333
334
335
336
337
    ``dict``-like object, where the function's actual return value is
    accessible via an attribute called `output`. All output arguments with a
    value of ``LOAD`` will be present as dictionary entries, with the keyword
    argument names used as keys. Any ``LOAD``ed output arguments which were not
    generated by the function will not be present in the dictionary.
Paul McCarthy's avatar
Paul McCarthy committed
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361


    **Example**


    As an example of using the ``fileOrArray`` decorator on a function
    which concatenates two files containing affine transformations, and
    saves the output to a file::

        # if atob, btoc, or output are passed
        # in as arrays, they are converted to
        # file names.
        @fileOrArray('atob', 'btoc', 'output')
        def concat(atob, btoc, output=None):

            # inputs are guaranteed to be files
            atob = np.loadtxt(atob)
            btoc = np.loadtxt(atoc)

            atoc = np.dot(btoc, atob)

            if output is not None:
                np.savetxt(output, atoc)

362
363
            return 'Done'

Paul McCarthy's avatar
Paul McCarthy committed
364
365
366
367

    Because we have decorated the ``concat`` function with :func:`fileToArray`,
    it can be called with either file names, or Numpy arrays::

368

Paul McCarthy's avatar
Paul McCarthy committed
369
370
        # All arguments are passed through
        # unmodified - the output will be
371
        # saved to a file called atoc.mat.
Paul McCarthy's avatar
Paul McCarthy committed
372
373
        concat('atob.txt', 'btoc.txt', 'atoc.mat')

374
375
376
377
378
379
380
381
382
        # The function's return value
        # is accessed via an attribute called
        # "output" on the dict
        assert concat('atob.txt', 'btoc.txt', 'atoc.mat').output == 'Done'

        # Outputs to be loaded into memory
        # are returned in a dictionary,
        # with argument names as keys.
        atoc = concat('atob.txt', 'btoc.txt', LOAD)['atoc']
Paul McCarthy's avatar
Paul McCarthy committed
383

384
385
386
387
388
389
390
391
392
        # In-memory inputs are saved to
        # temporary files, and those file
        # names are passed to the concat
        # function.
        atoc = concat(np.diag([2, 2, 2, 0]),
                      np.diag([3, 3, 3, 3]), LOAD)['atoc']


    **Using with other decorators**
Paul McCarthy's avatar
Paul McCarthy committed
393
394
395
396
397
398
399
400
401
402


    ``_FileOrThing`` decorators can be chained with other ``_FileOrThing``
    decorators, and other decorators.  When multiple ``_FileOrThing``
    decorators are used on a single function, the outputs from each decorator
    are merged together into a single dict-like object.


    ``_FileOrThing`` decorators can be used with any other decorators
    __as long as__ they do not manipulate the return value.
403
404
405
    """


406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
    class _Results(dict):
        """A custom ``dict`` type used to return outputs from a function
        decorated with ``_FileOrThing``. All outputs are stored as dictionary
        items, with the argument name as key, and the output object (the
        "thing") as value.

        The decorated function's actual return value is accessible via the
        :meth:`output` property.
        """
        def __init__(self, output):
            self.__output = output

        @property
        def output(self):
            """Access the return value of the decorated function. """
            return self.__output


    def __init__(self, prepIn, prepOut, load, *things):
Paul McCarthy's avatar
Paul McCarthy committed
425
426
        """Initialise a ``_FileOrThing`` decorator.

427
428
        :arg prepIn:  Function which returns a file name to be used in
                      place of an input argument.
Paul McCarthy's avatar
Paul McCarthy committed
429

430
431
        :arg prepOut: Function which generates a file name to use for
                      arguments that were set to :data:`LOAD`.
432

433
434
435
        :arg load:    Function which is called to load items for arguments
                      that were set to :data:`LOAD`. Must accept a file path
                      as its sole argument.
436

437
        :arg things:  Names of all arguments which will be handled by
438
439
440
                      this ``_FileOrThing`` decorator. If not provided,
                      *all* arguments passed to the function will be
                      handled.
441
442
443
444
445
446

        The ``prepIn`` and ``prepOut`` functions must accept the following
        positional arguments:

          - A directory in which all temporary input/output files should be
            stored
Paul McCarthy's avatar
Paul McCarthy committed
447

448
449
450
451
452
453
454
455
          - The name of the keyword argument to be processed

          - The argument value that was passed in
        """
        self.__prepIn  = prepIn
        self.__prepOut = prepOut
        self.__load    = load
        self.__things  = things
456
        self.__func    = None
Paul McCarthy's avatar
Paul McCarthy committed
457
458


459
    def __call__(self, *args, **kwargs):
460
        """Creates and returns the decorated function. """
Paul McCarthy's avatar
Paul McCarthy committed
461

462
463
464
465
466
467
        # the first call will be our decorated
        # function getting passed in.
        if self.__func is None:
            func        = args[0]
            self.__func = func
            return self
468

469
470
471
        # Subsequent calls will be calls
        # to the decorated function.
        else:
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
            return self.__wrapper(*args, **kwargs)


    def __get__(self, instance, owner):
        """Called when this ``_FileOrThing`` has been used to decorate a method
        of a class. When it is accessed on an instance, the instance is added
        as the first argument to the wrapper function.
        """
        if instance is None:
            return self
        else:
            wrapper = functools.partial(self.__call__, instance)
            return _update_wrapper(wrapper, self.__call__)


    def __wrapper(self, *args, **kwargs):
488
        """Function which calls ``func``, ensuring that any arguments of
Paul McCarthy's avatar
Paul McCarthy committed
489
        type ``Thing`` are saved to temporary files, and any arguments
Paul McCarthy's avatar
Paul McCarthy committed
490
        with the value :data:`LOAD` are loaded and returned.
491

492
        :arg func: The function being wrapped.
493

494
        All other arguments are passed through to ``func``.
495
        """
Paul McCarthy's avatar
Paul McCarthy committed
496

497
498
        func     = self.__func
        argnames = namedPositionals(func, args)
499
500

        # Create a tempdir to store any temporary
Paul McCarthy's avatar
Paul McCarthy committed
501
        # input/output things, but don't change
502
503
504
505
        # into it, as file paths passed to the
        # function may be relative.
        with tempdir.tempdir(changeto=False) as td:

506
507
            # Replace any things with file names.
            # Also get a list of LOAD outputs
508
509
            args, kwargs, outfiles = self.__prepareArgs(
                td, argnames, args, kwargs)
510
511

            # Call the function
512
            result = func(*args, **kwargs)
513

514
515
516
517
518
519
520
            # make a _Reults object to store
            # the output. If we are decorating
            # another _FileOrThing, the
            # results will get merged together
            # into a single _Results dict.
            if not isinstance(result, _FileOrThing._Results):
                result = _FileOrThing._Results(result)
521

522
523
            # Load the LOADed outputs
            for oname, ofile in outfiles.items():
524

525
526
                if not op.exists(ofile): oval = None
                else:                    oval = self.__load(ofile)
527

528
                result[oname] = oval
529

530
            return result
531
532


533
    def __prepareArgs(self, workdir, argnames, args, kwargs):
534
535
536
537
538
539
540
        """Prepares all input and output arguments to be passed to the
        decorated function. Any arguments with a value of :data:`LOAD` are
        passed to the ``prepOut`` function specified at :meth:`__init__`.
        All other arguments are passed through the ``prepIn`` function.

        :arg workdir: Directory in which all temporary files should be stored.

541
542
543
        :arg args:    Positional arguments to be passed to the decorated
                      function.

544
545
546
547
        :arg kwargs:  Keyword arguments to be passed to the decorated function.

        :returns:     A tuple containing:

548
549
550
                        - An updated copy of ``args``.

                        - An updated copy of ``kwargs``.
551
552
553

                        - A dictionary of ``{ name : filename }`` mappings,
                          for all arguments with a value of ``LOAD``.
554
555
        """

556
        outfiles = dict()
557

558
559
560
        allargs  = {k : v for k, v in zip(argnames, args)}
        allargs.update(kwargs)

561
562
        if len(self.__things) > 0: things = self.__things
        else:                      things = allargs.keys()
563

564
565
566
        for name in things:

            val = allargs.get(name, None)
567

568
            if val is None:
569
570
                continue

571
            if val is LOAD:
572
573
574
575

                outfile = self.__prepOut(workdir, name, val)

                if outfile is not None:
576
                    allargs[ name] = outfile
577
578
                    outfiles[name] = outfile
            else:
Paul McCarthy's avatar
Paul McCarthy committed
579

580
                infile = self.__prepIn(workdir, name, val)
Paul McCarthy's avatar
Paul McCarthy committed
581

582
                if infile is not None:
583
584
585
586
                    allargs[name] = infile

        args   = [allargs.pop(k) for k in argnames]
        kwargs = allargs
587

588
        return args, kwargs, outfiles
589
590


Paul McCarthy's avatar
Paul McCarthy committed
591
592
593
594
595
596
def fileOrImage(*imgargs):
    """Decorator which can be used to ensure that any NIfTI images are saved
    to file, and output images can be loaded and returned as ``nibabel``
    image objects.
    """

597
    def prepIn(workdir, name, val):
Paul McCarthy's avatar
Paul McCarthy committed
598

599
        infile = None
Paul McCarthy's avatar
Paul McCarthy committed
600
601

        if isinstance(val, nib.nifti1.Nifti1Image):
602
            infile = val.get_filename()
Paul McCarthy's avatar
Paul McCarthy committed
603
604
605

            # in-memory image - we have
            # to save it out to a file
606
607
            if infile is None:
                hd, infile = tempfile.mkstemp(fslimage.defaultExt())
Paul McCarthy's avatar
Paul McCarthy committed
608
                os.close(hd)
609
                val.to_filename(infile)
Paul McCarthy's avatar
Paul McCarthy committed
610

611
        return infile
Paul McCarthy's avatar
Paul McCarthy committed
612

613
614
    def prepOut(workdir, name, val):
        return op.join(workdir, '{}.nii.gz'.format(name))
Paul McCarthy's avatar
Paul McCarthy committed
615

616
    def load(path):
Paul McCarthy's avatar
Paul McCarthy committed
617
618
619
620
621
        # create an independent in-memory
        # copy of the image file
        img = nib.load(path)
        return nib.nifti1.Nifti1Image(img.get_data(), None, img.header)

622
    return _FileOrThing(prepIn, prepOut, load, *imgargs)
Paul McCarthy's avatar
Paul McCarthy committed
623
624
625
626
627
628
629


def fileOrArray(*arrargs):
    """Decorator which can be used to ensure that any Numpy arrays are saved
    to text files, and output files can be loaded and returned as Numpy arrays.
    """

630
    def prepIn(workdir, name, val):
Paul McCarthy's avatar
Paul McCarthy committed
631

632
        infile = None
Paul McCarthy's avatar
Paul McCarthy committed
633
634

        if isinstance(val, np.ndarray):
635
            hd, infile = tempfile.mkstemp('.txt')
Paul McCarthy's avatar
Paul McCarthy committed
636
            os.close(hd)
637
            np.savetxt(infile, val, fmt='%0.18f')
Paul McCarthy's avatar
Paul McCarthy committed
638

639
        return infile
Paul McCarthy's avatar
Paul McCarthy committed
640

641
642
    def prepOut(workdir, name, val):
        return op.join(workdir, '{}.txt'.format(name))
Paul McCarthy's avatar
Paul McCarthy committed
643

644
    load = np.loadtxt
Paul McCarthy's avatar
Paul McCarthy committed
645

646
    return _FileOrThing(prepIn, prepOut, load, *arrargs)