sylte 0.0.3

Pickling and unpickling of function arguments

sylte

Sylte provides a decorator that stores function arguments as a pickle file in a central location, and functions for retrieving those arguments later on, so that the function can be re-invoked with the same args. Useful when writing or debugging a function that exists somewhere near the end of a long-running pipeline.

Installation

Using poetry:

poetry add sylte

Using pipenv:

pipenv install sylte

Using pip:

pip install sylte

Usage

Let's say we have a function transform that we want to debug or modify. We will have to call it several times to see how it behaves with real data. It's normally called as part of a long-running pipeline, and we don't want to have to wait for this pipeline every time. We could write a unit-test, but perhaps we aren't yet sure how the output will look, and perhaps the input-data is complex and time-consuming to recreate in a test, and we'd prefer to do that when the function is finalized, to avoid having to repeatedly modify the test as the function is modified.

Enter sylte. By applying the @sylt decorator to the function and running the pipeline once, the args are recorded, and can be retrieved later.

from sylte import sylt

@sylt
def transform(this_huge_df, this_other_huge_df, this_object_with_lots_of_attributes):
    ...

The arg set will be stored in a pickle file in the default cache location for the os. The location can be seen by running from sylte import CACHE_DIR; print(CACHE_DIR). To use a different location than the default, specify the location with the environment variable SYLTE_CACHE_DIR.

The file name will have the format <file name>-<function name>-<timestamp>.pickle.

The function latest will retrieve an unsylt the latest arg set, returning a tuple with args and kwargs.

>>> from sylte import latest
...
>>> args, kwargs = latest()
>>> transform(*args, **kwargs)

show returns a list of all sylted arg sets:

>>> from sylte import show
...
>>> show()
['demo-transform-2022-01-14-15-08-59',
 'demo-transform-2022-01-14-15-12-33',]

unsylt unsylts and returns the arg set with the specified name as output by show, i.e. the filename with the extension omitted:

>>> from sylte import unsylt
...
>>> args, kwargs = unsylt('demo-add-2022-01-14-15-08-59')
>>> transform(*args, **kwargs)

clear deletes all previously sylted arg sets:

>>> from sylte import clear, show
...
>>> clear()
>>> show()
[]