lazyr

Creates lazily-imported modules in a more readable and safer way.

A lazily-imported module (or a lazy module, to be short) is not physically loaded in the Python environment until its attributes are being accessed. This could be useful when you are importing some modules that are hardly used but take a lot of time to be loaded.

README.md

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• zh_CN 简体中文

Installation

$ pip install lazyr

Usage

Make a lazy module

Make pandas become a lazy module, for example:

>>> import lazyr
>>> lazyr.register("pandas") # pandas is a lazy module from now on
LazyModule(pandas)

>>> import pandas as pd # pandas is not loaded because it's lazy
>>> pd
LazyModule(pandas)

>>> df = pd.DataFrame # pandas is actually loaded now
>>> df
<class 'pandas.core.frame.DataFrame'>

There is also a simpler way to create a lazy module, but it may cause type hints to lose efficacy:

>>> import lazyr
>>> pd = lazyr.register("pandas")
>>> pd
LazyModule(pandas)

Check if a module is lazy

Use islazy() to check if a module is lazy or not:

>>> lazyr.islazy(pd)
True

Wake up a module

The lazy modules are not physically loaded until their attrubutes are imported or used, but sometimes you may want to activate a lazy module without accessing any of its attributes. On that purpose, you can 'wake' up the module like this:

>>> lazyr.wakeup(pd) # pandas is woken up and loaded
>>> lazyr.islazy(pd)
False

Ignore attributes

You can make a module even lazier by setting the ignore parameter of register(), which specifies the names of attributes to be ignored. The values of the ignored attributes will be set to None, and a lazy module will no longer be activated by the access to them.

>>> import lazyr
>>> lazyr.register("pandas", ignore=["DataFrame", "Series"]) # Ignoring DataFrame and Series
LazyModule(pandas, ignore=['DataFrame', 'Series'])

>>> from pandas import DataFrame # pandas is not loaded; DataFrame is set to None
>>> from pandas import Series # pandas is not loaded; Series is set to None
>>> from pandas import io # pandas is loaded because 'io' is not an ignored attribute

>>> from pandas import DataFrame # DataFrame is loaded this time 
>>> DataFrame
<class 'pandas.core.frame.DataFrame'>

Logging

Specify the verbose parameter when calling register() to see what exactly will happen to a lazy module during the runtime:

>>> import lazyr
>>> _ = lazyr.register("pandas", verbose=2)
INFO:lazyr:import:pandas

>>> import pandas as pd
DEBUG:lazyr:access:pandas.__spec__

>>> df = pd.DataFrame
DEBUG:lazyr:access:pandas.DataFrame
INFO:lazyr:load:pandas(.DataFrame)

See Also

Github repository

• https://github.com/Chitaoji/lazyr/

PyPI project

• https://pypi.org/project/lazyr/

License

This project falls under the BSD 3-Clause License.

History

v0.0.16

• New function islazy(), for checking the status of a module.
• Improved the representational strings of lazy modules.

v0.0.15

• Various improvements.

v0.0.12

• Prettier logs.

v0.0.11

• Fixed the meta-data.
• Performance enhancements.

v0.0.9

• Updated LICENSE.

v0.0.7

• Removed unnecessary objects from the main lazyr namespace.

v0.0.6

• Improved logging:
  • Created a separate logger named 'lazyr' for lazy modules;
  • More detailed logs when verbose > 0.

v0.0.4

• LazyModule no longer activated by _ipython_*() or _repr_*() methods.

v0.0.3

• Various improvements.

v0.0.2

• New function wakeup(), for compulsively activating modules.

v0.0.1

• Initial release.