Lazify

0.4.0 · maintenance · verified Tue Apr 14

Lazify aims to be the defacto standard and most complete library for Python tools related to lazy evaluation. It is designed for deferred computation, evaluating expressions or attributes only when they are first accessed. The current version is 0.4.0, released in 2018, indicating a lack of active maintenance and a very slow release cadence.

Warnings

gotcha The `lazify` library has not been updated since June 2018. This indicates a lack of active maintenance, meaning it may not receive bug fixes, security patches, or new features. Users should be aware of potential long-term support issues.
Fix: Consider evaluating alternatives if active development and support are critical for your project. If using `lazify`, thoroughly test its compatibility and behavior in your specific environment.
gotcha While PyPI metadata states compatibility with Python 2 and 3, the last release was in 2018. There is a high likelihood of encountering compatibility issues with modern Python versions (e.g., Python 3.9+) that have introduced new syntax or removed deprecated features not present in 2018.
Fix: Test `lazify` thoroughly with your target Python version. If issues arise, consider pinning an older, compatible Python version or refactoring your code to use an alternative lazy evaluation mechanism.
gotcha This library focuses on lazy *evaluation* of expressions and object attributes, not on dynamically loading entire Python *modules* only when they are first used (a concept sometimes referred to as 'lazy import'). While related to performance, `lazify`'s scope is distinct from tools designed for deferred module loading.
Fix: Ensure that `lazify` aligns with your specific use case. If you intend to lazily load modules, investigate Python's `importlib.util.LazyLoader` or other dedicated 'lazy import' solutions.

Install

pip install lazify Install latest version

Imports

lazy
```
from lazify import lazy
```
Decorator for lazy evaluation of methods.
LazyProxy
```
from lazify import LazyProxy
```
Class for creating lazy objects that evaluate an expression upon first access.

Quickstart

This quickstart demonstrates how to use `LazyProxy` for general lazy evaluation and the `@lazy` decorator for lazy attributes within classes. The decorated method or proxied function is only executed upon its first access, and its result is then cached for subsequent calls.

from lazify import LazyProxy, lazy

# Example 1: LazyProxy for deferred expression evaluation
def expensive_calculation():
    print("  [TRACE] Performing expensive calculation inside function...")
    return 42

print("Creating LazyProxy object...")
lazy_value = LazyProxy(expensive_calculation)
print("LazyProxy created, but calculation not yet performed.")

print(f"First access to lazy_value: {lazy_value}") # This triggers the calculation
print(f"Second access to lazy_value: {lazy_value}") # This uses the cached result

print("\n" + "-" * 20 + "\n")

# Example 2: @lazy decorator for lazy attributes in a class
class MyClass:
    def __init__(self, initial_value):
        self._initial_value = initial_value

    @lazy
    def processed_value(self):
        print(f"  [TRACE] Processing value {self._initial_value} with decorator...")
        return self._initial_value * 2

obj = MyClass(10)
print("MyClass instance created, 'processed_value' not yet computed.")

print(f"First access to obj.processed_value: {obj.processed_value}") # This triggers the processing
print(f"Second access to obj.processed_value: {obj.processed_value}") # This uses the cached result

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