How to Achieve the Equivalent of Java\'s Class.forName() in Python?

Python's Flexible Reflection: Equivalent to Java's Class.forName()

Python's reflection capabilities are significantly more versatile and user-friendly compared to Java's Class.forName(). While there may not be an exact direct equivalent, understanding Python's reflection mechanisms allows you to achieve similar functionality.

Python's Reflection Approach

Python's reflection utilizes several essential techniques:

1. __import__: Imports a module given its name as a string.
2. getattr: Retrieves an attribute (module, class, function, etc.) from a specified object.
3. Looping: Iteratively obtains references to nested modules and classes within a fully qualified name.

Custom Function: get_class

To provide an equivalent functionality to Class.forName(), the following Python function can be utilized:

<code class="python">def get_class(kls):
    parts = kls.split('.')
    module = '.'.join(parts[:-1])
    m = __import__(module)
    for comp in parts[1:]:
        m = getattr(m, comp)
    return m</code>

Usage Example

This function enables you to obtain a class reference from its fully qualified name:

<code class="python">>>> D = get_class("datetime.datetime")
>>> D
<type 'datetime.datetime'>
>>> D.now()
datetime.datetime(2009, 1, 17, 2, 15, 58, 883000)</code>

How it Works

• The class name is split into its component parts (module name and class name).
• The module is imported using __import__.
• getattr is repeatedly employed to traverse through nested modules and obtain the final class reference.

Conclusion

Python's reflection offers a powerful and flexible way to manipulate classes and objects. While it differs from Java's Class.forName(), it provides a more adaptable and feature-rich approach to achieve similar goals.

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