Chat GPT and Google Gemini Answer Programming Questions
Introduction
I believe that large language models (LLMs) are the most amazing thing that has happened in my lifetime—frankly, by a long stretch1. While they are a bit of a cheat, because they incorporate everything that mankind knows as part of their training, their ability to understand is truly astonishing. I use these models multiple times an hour when I am working and find them incredibly helpful.
Google recently announced an upgrade, Gemini Advanced, of their model. I thought it would be interesting to compare it with ChatGPT4, which has been my go to model for the last few months. The examples below are a series of fairly technical object oriented programming questions in Python. In each case, I show the question first, followed by the two responses and then some commentary. The questions are as entered and contain typos—both models are tolerant of typos.
The comparison is not quite apples-to-apples because in GPT I have standing instructions. I can’t see how to enter those in Gemini yet.
Question 1
I am using quarto markdown to create a blog. I want to do a side by side comparison of various things. I think I can do that in markdown with :::{class info} using boostrap classes for columns? How?
Response Using GPT Answer
ChatGPT 4
To create a side-by-side comparison of various items in Quarto using markdown with Bootstrap classes, you can use the :::{.row}
and :::{.col}
syntax provided by Quarto to leverage Bootstrap’s grid system. This approach allows you to create responsive side-by-side layouts. Here’s how you can do it:
:::{.row}
:::{.col-md-6}### Item 1
- Feature A
- Feature B
- Feature C
:::
:::{.col-md-6}### Item 2
- Feature X
- Feature Y
- Feature Z
::: :::
In this example: - :::{.row}
starts a new row. - :::{.col-md-6}
creates a column that spans 6 out of 12 possible column widths on medium-sized screens (and larger) for each item. This effectively divides the row into two columns for side-by-side comparison. - Inside each :::{.col-md-6}
block, you can place the content you want to compare (e.g., ### Item 1
and ### Item 2
with their respective features listed).
Adjust the -md-
part and the number (e.g., 6
in .col-md-6
) based on your responsive design needs: - Use -sm-
, -md-
, -lg-
, or -xl-
to target different screen sizes. - Adjust the column span number (e.g., 4
, 6
, 8
) to change the width of each column within the 12-column grid system.
Remember, this approach assumes your Quarto document is using Bootstrap or a theme that includes Bootstrap.
Google Gemini
Absolutely! You can use Quarto’s ability to incorporate custom CSS classes along with Bootstrap’s grid system to achieve side-by-side comparisons in your blog. Here’s how to do it:
1. Column Setup
Here’s the core Markdown structure using column layout divs:
:::{.columns}
::: {.column width="50%"}
**Content for the First Column**
Your comparison details, text, images, etc. for the first item would go here.
:::
::: {.column width="50%"}
**Content for the Second Column**
Your comparison details for the second item would go here.
::: :::
Explanation:
:::{.columns}
: Creates an outer container for the side-by-side columns.::: {.column width="50%"}
: Each of these defines an individual column. Thewidth="50%"
ensures they’ll take up half the available space, creating a two-column layout.
2. Adding Content
You can place any valid Markdown or HTML content within each .column
div. For example:
:::{.columns}
::: {.column width="50%"}## Item 1
* Feature A
* Feature B
[Image of Item 1](item1.jpg)
:::
::: {.column width="50%"}## Item 2
* Feature X
* Feature Y
[Image of Item 2](item2.jpg)
::: :::
3. (Optional) Styling with Bootstrap Classes
If you want more refined control using Bootstrap’s grid classes, you can adjust the .column
divs accordingly. For example:
:::{.columns}
::: {.column .col-md-6}
...content...
:::
::: {.column .col-md-6}
...content...
::: :::
Remember that for Bootstrap classes to work effectively, you’ll need to include the Bootstrap CSS in your Quarto document.
Tips
- Experiment with the
width
percentages or Bootstrap’s column classes (col-sm-
,col-md-
, etc.) to get the exact side-by-side layout you need. - Consider adding extra CSS rules in your Quarto document to customize the appearance of the comparison further (e.g., borders, padding, etc.).
Let me know if you have any specific comparison scenarios, and I can help you tailor the code further!
Response Using Google’s Answer
ChatGPT 4
To create a side-by-side comparison of various items in Quarto using markdown with Bootstrap classes, you can use the :::{.row}
and :::{.col}
syntax provided by Quarto to leverage Bootstrap’s grid system. This approach allows you to create responsive side-by-side layouts. Here’s how you can do it:
:::{.row}
:::{.col-md-6}### Item 1
- Feature A
- Feature B
- Feature C
:::
:::{.col-md-6}### Item 2
- Feature X
- Feature Y
- Feature Z
::: :::
Etc.
Google Gemini
Absolutely! You can use Quarto’s ability to incorporate custom CSS classes along with Bootstrap’s grid system to achieve side-by-side comparisons in your blog. Here’s how to do it:
1. Column Setup
Here’s the core Markdown structure using column layout divs:
:::{.columns}
::: {.column width="50%"}
**Content for the First Column**
Your comparison details, text, images, etc. for the first item would go here.
:::
::: {.column width="50%"}
**Content for the Second Column**
Your comparison details for the second item would go here.
::: :::
Etc.
Commentary
GPT answered the question because it used Bootstrap, but the answer didn’t work very well. The Google answer achieved the desired effect. The rest of this post uses the Google answer tweaked to have space between the columns.
Question 2
I have the following two classes. Is it correct that B is derived from A? In the constructor for B how do I call the constructor for A with argument x?
class A():
def __init__(self, x):
self.x = x
class B(A):
def __init__(self, x, y):
self.y = y
?? constructor for A
Responses
ChatGPT 4
Yes, class B is derived from class A in your example. To call the constructor of class A from the constructor of class B, you use the super()
function. Here’s how you can do it:
class A():
def __init__(self, x):
self.x = x
class B(A):
def __init__(self, x, y):
super().__init__(x) # This calls the constructor of class A with the argument x
self.y = y
The super().__init__(x)
call within B
’s constructor invokes the constructor of the superclass A
, passing x
as the argument. This way, A
’s constructor is responsible for handling the x
attribute, while B
’s constructor handles the additional attributes or operations specific to B
, such as setting the y
attribute in this case.
Google Gemini
Absolutely, you’re correct! Here’s a breakdown of why and how to call the parent class constructor:
Inheritance
The syntax class B(A)
signifies that class B
is derived from class A
. This is the principle of inheritance in object-oriented programming. The derived class (B
) inherits the attributes and methods of the base class (A
).
Constructor Calling
To properly initialize an instance of B
, you need to ensure that the attributes from both class A
and class B
are set up. Here’s how you call A
’s constructor from within B
’s constructor:
class B(A):
def __init__(self, x, y):
super().__init__(x) # Call A's constructor
self.y = y
Explanation
super()
: This function gives you access to the parent class (A
) from within the derived class (B
).super().__init__(x)
: This line explicitly calls the parent class’s constructor (__init__
) and passes the argumentx
to it. This ensures that thex
attribute in classA
is initialized correctly.
Key Points
- In Python, it’s important to call the parent class’s constructor when creating a derived class. This guarantees that the inherited attributes are properly set up.
- The
super()
function makes working with inheritance much easier.
Let me know if you’d like a more elaborate example or further explanations of object-oriented concepts!
Commentary
Both answers on point and informative. My standing instructions to GPT favor shorter responses.
Question 3
Pls tell me more aout super. I find it very mysterious. How does it work if B is dervied from A1 and A2 and A3, for example? Or from A and C and C is in turn dervied from D?
Responses
ChatGPT 4
The super()
function in Python is used to give access to methods in a superclass from a subclass that inherits from it. It’s particularly powerful and somewhat complex when dealing with multiple inheritance, where a class is derived from more than one base class.
Basic Usage
In a single inheritance scenario, super()
is straightforward: it allows you to call methods of the superclass in your subclass. The common use case is to extend the functionality of the superclass method in the subclass by either calling the superclass method before executing additional logic in the subclass method or doing so afterward.
Multiple Inheritance
Python supports multiple inheritance, where a class can inherit from more than one class. This introduces complexity, especially in how super()
behaves. Python’s method resolution order (MRO) comes into play in these scenarios.
Method Resolution Order (MRO)
Python uses the C3 linearization algorithm to establish an MRO in multiple inheritance scenarios. The MRO determines the order in which base classes are searched when executing a method. You can view the MRO of a class using the .__mro__
attribute or the mro()
method.
Example with Multiple Inheritance
Consider the following classes:
class A:
def __init__(self):
print("A", end=" ")
super().__init__()
class B(A):
def __init__(self):
print("B", end=" ")
super().__init__()
class C(A):
def __init__(self):
print("C", end=" ")
super().__init__()
class D(B, C):
def __init__(self):
print("D", end=" ")
super().__init__()
In this case, D
is derived from both B
and C
. If you instantiate D
, the output will illustrate the MRO:
= D() d
Output might be: D B C A
This output is the result of the C3 linearization that Python uses to resolve the order in which methods should be called. You can check the MRO by:
print(D.mro())
super()
in Multiple Inheritance
When you call super()
in a class that’s part of a multiple inheritance hierarchy, Python follows the MRO to determine which superclass method to invoke. This ensures that each method in the hierarchy is called in a specific, predictable order, avoiding the problem of a method being called more than once.
super()
with Arguments
In Python 3, super()
called without arguments is equivalent to super(ThisClass, self)
, automatically passing the class and instance to super()
. In complex inheritance hierarchies, super()
works with the MRO to ensure the correct superclass method is called next.
Summary
super()
is essential for accessing superclass methods in a subclass.- In multiple inheritance scenarios, the MRO determines the order in which superclass methods are called.
- Python’s use of the C3 linearization algorithm ensures a consistent and predictable MRO.
- Understanding
super()
and MRO is crucial for correctly implementing and extending methods in complex inheritance hierarchies.
Google Gemini
You’re right! super()
can seem a bit mysterious, especially in scenarios with multiple inheritance. Let’s unravel that mystery:
How super()
Works
The core idea behind super()
is to help navigate the inheritance hierarchy in a dynamic way. Here’s what happens under the hood:
Method Resolution Order (MRO): When you use
super()
, Python doesn’t just look at the immediate parent class ofB
. It analyzes the entire inheritance chain using an algorithm called the Method Resolution Order (MRO). The MRO determines the order in which classes are searched when you try to access a method (like__init__
).Delegation: Inside your
B
class’s method,super()
essentially says, “Don’t execute the method here; find the next version of this method up the inheritance chain and execute that one.”
Example: Multiple Inheritance
Let’s say you have this structure:
class A1:
def __init__(self):
print("A1 init")
class A2:
def __init__(self):
print("A2 init")
class A3:
def __init__(self):
print("A3 init")
class B(A1, A2, A3):
def __init__(self):
super().__init__()
If you create an instance of B
, the super().__init__()
call would follow the MRO to initialize classes in a specific order, You might see output like this, reflecting the order in which constructors are called:
A1 init
A2 init
A3 init
Example: Deeper Inheritance
Now, consider this scenario:
class D:
def __init__(self):
print("D init")
class C(D):
def __init__(self):
super().__init__()
print("C init")
class A:
def __init__(self):
print("A init")
class B(A, C):
def __init__(self):
super().__init__()
Again, super()
would follow the MRO, and your output might look like this:
D init
C init
A init
Key Points
super()
’s behavior is determined by the Method Resolution Order, ensuring a predictable chain of method calls even in complex inheritance relationships.- This dynamic resolution is what makes
super()
particularly useful in multiple inheritance scenarios where the exact inheritance structure might change.
Let me know if you want a specific example with some attributes and method calls to make it even more concrete!
Commentary
GPT brings up the C3 linearization algorithm, which is a level of detail I appreciate. Basic GPT example has more depth, but Gemini follows up with a better nested inheritance structure. GPT touches on the arguments to super
.
Question 4
If B derives from A, you call B the subclass and A the super class?
Responses
ChatGPT 4
Yes, that’s correct. In the context of inheritance in object-oriented programming:
- A is referred to as the superclass (or base class, parent class), because it is the class from which another class (the subclass) inherits.
- B, which derives from A, is called the subclass (or derived class, child class) because it inherits from the superclass.
The subclass extends or modifies the behavior defined in the superclass. This mechanism allows for code reuse and polymorphism, making it easier to maintain and extend the functionality of your software.
Google Gemini
Absolutely! You got the terminology right. In the inheritance relationship where B derives from A:
- B is the subclass (also called derived class or child class). It inherits properties and behaviors from its parent.
- A is the superclass (also called base class or parent class). It provides the foundation for the subclass to build upon.
Let me know if you have any other questions on the topic!
Commentary
I just find the terminology confusing and neither answer convinced me it is logical. It’s just the child’s question, “But, why is a cow a cow?”
Question 5
that feels upsidedown to me!
Responses
ChatGPT 4
It’s understandable that the terminology might feel counterintuitive at first! The terms “superclass” and “subclass” can indeed seem a bit abstract or even upside down, especially when you’re starting to grasp the concepts of inheritance and object-oriented programming. Here’s a way to think about it that might help:
Superclass (Base Class, Parent Class): Think of the superclass as the “foundation” or “base” upon which subclasses are built. It’s “super” in the sense that it provides the basic attributes and methods from which other classes can inherit. It’s a general, broader classification.
Subclass (Derived Class, Child Class): The subclass is considered “below” the superclass in the hierarchy, not in importance, but because it specializes or extends the superclass. It inherits from the superclass, adding more specific features or overriding existing ones to differentiate itself. It’s a more specific, detailed classification built on top of the superclass.
In a family tree analogy, the superclass is like a parent, while the subclass is like a child. The child inherits traits from the parent but can also have its unique characteristics or override inherited traits with new ones.
Despite the initial confusion, these terms are widely used in object-oriented programming to describe relationships between classes in a hierarchy, emphasizing the direction of inheritance from the more general to the more specific.
Google Gemini
I totally understand why that might feel upside-down! Here’s a couple of perspectives that might help you see why these terms make sense:
1. Building Blocks:
- Think of the superclass as the foundation or the base component upon which other classes are built. It’s on top in the sense that it lays the groundwork.
- The subclass is like a more specialized version of the base class. It adds upon or refines what the superclass provides, and thus sits ‘below’ the foundation in the hierarchy.
2. Tree Analogy:
- Visualize an inheritance hierarchy as an upside-down family tree.
- The superclass would be like a grandparent at the very top of the tree.
- Subclasses would be like their children, and any further derived classes would be like grandchildren, branching downwards.
3. “Super” as in “Superset”:
- The superclass holds a ‘superset’ of the characteristics that all its subclasses inherit. That’s why the word ‘super’ makes sense; it encompasses the broader properties.
- Subclasses are ‘subsets’ within this broader class structure.
It’s Not Perfect
It’s worth noting that no analogy is perfect. Terms like “super” and “sub” sometimes get mixed up due to their connotations in everyday language. The core to remember is the direction of inheritance – subclasses build upon and extend from the foundation of the superclass.
Would you like some more visual examples to help solidify the concept?
Commentary
Gotta love Gemini’s “It’s on top in the sense that it lays the groundwork.” Possible hint of non-human writing. I still find the nomenclature confusing.
Question 6
Again, I have the following situation. I have a = A() existing. I then want to create a B object that “wraps” that A, something like b = B(a). How can I do that? A expects a string (say), not a class A instance. Do you see what I mean?
class A():
def __init__(self, x):
self.x = x
class B(A):
def __init__(self, x, y):
super().__init__(x) # This calls the constructor of class A with the argument x
self.y = y
Responses
ChatGPT 4
If you want to create a class B
that “wraps” an instance of class A
rather than inheriting from A
, you shouldn’t inherit B
from A
. Instead, B
should take an instance of A
as an argument and store it as an attribute. This way, B
can use or modify A
’s behavior or data as needed. Here’s how you can do it:
class A():
def __init__(self, x):
self.x = x
class B():
def __init__(self, a_instance, y):
self.a_instance = a_instance # Store the instance of A
self.y = y
# Example method to demonstrate accessing A's attributes/methods from B
def show_x_and_y(self):
print("A's x:", self.a_instance.x)
print("B's y:", self.y)
In this design, B
does not inherit from A
, so it doesn’t call A
’s constructor with super().__init__(x)
. Instead, B
takes an existing instance of A
as an argument along with its own data (y
) and stores it. This allows B
to “wrap” A
, accessing or modifying A
’s attributes and methods through the stored instance (self.a_instance
).
Here’s how you could use these classes:
# Create an instance of A
= A("some string")
a
# Create an instance of B, wrapping the instance 'a' of A
= B(a, "another string")
b
# Use B's method to demonstrate access to both A and B's data
b.show_x_and_y()
This approach allows B
to act as a wrapper for A
, providing additional functionality or storing additional data while still having access to the wrapped A
instance’s attributes and methods. This pattern is useful in various scenarios, such as when you want to extend the functionality of a class without modifying it directly (a form of composition).
Google Gemini
You’re right! There seems to be a mismatch in your goal and the code structure. Let me explain and offer a solution:
The Issue
- Inheritance vs. Composition: Your original question phrasing (“wraps that A”) suggests composition, rather than inheritance. When one object “wraps” another, it has an instance of the other object as a part of it, not is an instance of it.
- Type Mismatch: Class
A
’s constructor expects a string, but if you use inheritance as shown, you’re trying to pass it an existing instance ofA
.
Solution: Composition
Here’s how you can modify your code to achieve the “wrapping” behavior using composition:
class A:
def __init__(self, x):
self.x = x
class B:
def __init__(self, a_obj):
self.a_obj = a_obj # Store the A object
# Create an A object
= A("some string")
a
# Create a B object that wraps the A object
= B(a)
b
# Access the value of x through the B object
print(b.a_obj.x) # Output: "some string"
Explanation
- No Inheritance: We’ve removed the inheritance relationship (
class B(A)
). Now,B
is an independent class. - Storing the Object: Instead of calling
A
’s constructor insideB
, we now accept an instance ofA
(a_obj
) inB
’s constructor and store it as an attribute (self.a_obj
).
Benefits of Composition
- Flexibility:
B
can now work with any instance ofA
, not just ones directly created inside its constructor. - Clearer Separation: This avoids tight coupling between the classes that can arise from inheritance, enhancing reusability.
Let me know if you have any further questions or want to explore more complex scenarios of how different classes can interact with each other!
Commentary
Both suggesting a member variable, which Gemini calls composition.
Question 7
I see that, but A exposes a lot of methods that I want to be able to call directly in B, not self.Aobject.method, just self.method. THis must be a standard thing is OOP, that you want to dynamically extend an object? I don’t want a big A with too many methods, as I only need B occasionally. What is the best pattern to use? Really looking for you help here! THis is a problem I faced on numerous occasions!
Responses
ChatGPT 4
Given your requirements, it sounds like you’re looking for a way to dynamically extend an object’s functionality in a flexible manner, without permanently adding more methods to the base class (A
) and while maintaining the ability to call A
’s methods directly from an instance of B
as if they were its own. This scenario calls for a design pattern that allows for such flexibility, typically achieved through composition or the use of a proxy pattern.
One approach that aligns well with your needs is the Proxy Pattern, specifically a variation known as the Delegation Pattern. Instead of inheriting from class A
, class B
holds an instance of A
and delegates calls to it. You can automate delegation in Python using the __getattr__
method to dynamically forward method calls to the A
instance.
Here’s how you might implement this:
class A:
def __init__(self, x):
self.x = x
def method_a(self):
print(f"Method in A, x = {self.x}")
class B:
def __init__(self, a_instance, y):
self._a_instance = a_instance
self.y = y
def __getattr__(self, name):
"""Delegate attribute access to the A instance if attribute not found in B."""
return getattr(self._a_instance, name)
# B's specific methods can be defined here
def method_b(self):
print(f"Method in B, y = {self.y}")
# Usage
= A("Hello from A")
a = B(a, "Hello from B")
b
# This will call A's method_a through B
b.method_a() # This will directly call B's method_b b.method_b()
In this implementation, B
does not inherit from A
. Instead, it “wraps” an instance of A
. When you try to access an attribute or method on an instance of B
that doesn’t exist in B
, Python’s __getattr__
method is called. Here, __getattr__
is used to delegate those calls to the wrapped A
instance. This allows you to call methods of A
directly on an instance of B
without the need for B
to explicitly define or know about those methods.
Key Points:
- Flexibility: This approach allows
B
to extendA
dynamically, without hardcoding method names or altering the structure ofA
. - Maintainability: It keeps
A
’s implementation clean and focused, only adding functionality inB
when necessary. - Transparency: To the user of class
B
, it appears as ifB
has all methods ofA
, providing a seamless interface.
Considerations:
- Performance: Using
__getattr__
introduces a slight overhead because of the dynamic method resolution. - Debugging: Debugging can be slightly more complex due to the indirection added by
__getattr__
. - Method Overriding: If
B
needs to override a method fromA
and also call the original method fromA
, you’ll have to handle that explicitly inB
.
This pattern provides a powerful way to dynamically extend objects in Python, accommodating scenarios where inheritance might be too rigid or when you want to avoid bloating base classes with methods that are only occasionally needed.
Google Gemini
Absolutely, your requirement makes perfect sense! There are indeed a few standard OOP patterns that help you dynamically extend existing objects with minimal fuss. Let’s explore the most suitable ones:
1. The Proxy Pattern
Concept: You create a “proxy” object that mimics the interface of the original object (
A
in your case). This proxy internally holds a reference to the original object, and then delegates actual method calls to that internal object.How it Helps:
- Selective Exposure: The proxy object lets you control which methods from
A
you want to directly expose, keepingB
’s interface clean. - Lazy Creation: You could instantiate the internal
A
object only when needed, saving resources ifB
’s capabilities are used occasionally.
- Selective Exposure: The proxy object lets you control which methods from
Code Example (Simplified):
class A:
def method1(self):
# ...
def method2(self):
# ...
class B:
def __init__(self):
self._a = None # Placeholder for A object
def method1(self):
if not self._a:
self._a = A() # Create A on demand
return self._a.method1() # Delegate
2. The Adapter Pattern
Concept: When you have an existing object (
A
) but its interface doesn’t quite align with how you want to use it inB
. The adapter provides a “translation layer”.How it Helps
- Interface Adaptation: An adapter class can take calls designed for
B
and transform them into the appropriate actions onA
, even if the method names don’t match perfectly.
- Interface Adaptation: An adapter class can take calls designed for
3. Mixins
Concept: Small, reusable classes designed for adding specific functionality. Can be ‘mixed into’ an inheritance hierarchy. (Note: Python’s multiple inheritance makes this easier).
How it Helps:
- Focused Features: Break down specific behaviors of
A
that you need inB
into mixin classes, and include only those needed forB
.
- Focused Features: Break down specific behaviors of
Choosing the Right Pattern
- Proxy: Useful if you want direct access to most of
A
’s methods and potential lazy creation. - Adapter: Better when there’s a mismatch in how
A
’s methods work and how you want to use them inB
. - Mixins: A good choice if you can factor out the required pieces of functionality from
A
into well-defined, reusable mixin classes.
Important Note: Overusing any of these patterns can lead to complexity. Assess how many of A
’s methods you truly need in B
and make a design choice based on simplicity and clarity.
Let me know if you’d like a more detailed example of any of these patterns in action!
Commentary
Both get to the Proxy Pattern, but offer slightly different solutions. The GPT solution is exactly what I wanted, and seems very nice. It leverages built in Python and avoid having to name methods. The Gemini solution is less general.
Question 8
Isn’t there a getattr and getattribute with subtly different properties? can you explain?
Note: Gemini hadn’t brought this up previously.
Responses
ChatGPT 4
Yes, in Python, both __getattr__
and __getattribute__
methods exist, and they do have subtly different behaviors and use cases when it comes to attribute access in classes.
__getattribute__
- Always Called:
__getattribute__
is called for every attempt to access an attribute, regardless of whether the attribute exists or not. It’s a part of the lookup chain for any attribute access on an object. - Override with Caution: Because
__getattribute__
is called for every attribute access, overriding it requires careful handling to avoid infinite recursion. When you override__getattribute__
, you typically usesuper().__getattribute__(name)
within it to safely access attributes of the superclass without recursion. - Use Case: You might override
__getattribute__
if you need to intercept every attribute access, which could be useful for debugging, logging, or implementing proxies where you need to handle all attribute accesses dynamically.
Example:
class A:
def __init__(self):
self.x = 'X'
def __getattribute__(self, name):
print(f"Accessing {name}")
return super().__getattribute__(name)
= A()
a print(a.x) # This will print "Accessing x" followed by "X"
__getattr__
- Called as a Fallback:
__getattr__
is only called if the attribute was not found by the usual means. It acts as a fallback method for attribute access, which makes it useful for catching attempts to access missing attributes without affecting normal attribute access. - Use Case:
__getattr__
is suitable when you want to provide a default behavior for missing attributes, such as returning a default value, generating attributes on the fly, or forwarding attribute access to another object (as in delegation or proxy patterns).
Example:
class B:
def __getattr__(self, name):
return f"{name} does not exist"
= B()
b print(b.some_missing_attribute) # This will print "some_missing_attribute does not exist"
Key Differences
- Invocation:
__getattribute__
is called for every attribute access, making it very powerful but also risky if not handled correctly due to the potential for infinite recursion.__getattr__
is called only when an attribute is not found by the normal lookup process. - Purpose:
__getattribute__
can be used to intercept all attribute accesses, which is useful for low-level control or proxying.__getattr__
is more suited for providing fallback behavior for missing attributes or for cases where attributes are to be generated dynamically.
Choosing between __getattribute__
and __getattr__
depends on your specific needs for attribute access and interception, and understanding their differences is key to using them effectively.
Google Gemini
Absolutely! You’re referring to two special methods in Python that are important for handling attribute access:
1. __getattribute__
- The Gatekeeper:
__getattribute__
is called for every attribute access attempt for an object, regardless of whether the attribute actually exists or not. It has ultimate control over how attributes are fetched. - Default Behavior: If you don’t define
__getattribute__
in your class, Python has a default implementation that does the standard attribute lookup through an instance’s__dict__
(its internal dictionary of attributes) and walks up the inheritance chain if needed. - Customization: If you do define
__getattribute__
, you override this default behavior, allowing you to intercept all attribute access and implement custom logic.
2. __getattr__
- Fallback Handler:
__getattr__
is called only when the normal attribute lookup has failed. This means the attribute wasn’t found in the object’s__dict__
or through its inheritance chain. - Providing Defaults: A common use for
__getattr__
is to provide default values when certain attributes don’t exist. - Dynamic Attributes: It’s also useful for creating objects with attributes that can be generated on the fly.
Relationship & Example
class MyClass:
def __init__(self):
self.val = 10
def __getattribute__(self, name):
print("Calling __getattribute__")
return super().__getattribute__(name)
def __getattr__(self, name):
print("Calling __getattr__")
return f"Default value for '{name}'"
= MyClass()
obj
print(obj.val) # Calls __getattribute__
print(obj.nonexistent) # Calls __getattribute__, then __getattr__
Key Differences
Feature | __getattribute__ |
__getattr__ |
---|---|---|
Scope | Called for every attribute access attempt | Called only when attribute is not found |
Priority | Highest priority | Falls back when __getattribute__ doesn’t find attribute |
Default Behavior | Python has a built-in default | No default implementation |
Common Use Case | Dynamic attribute lookup; controlling access | Providing default values; dynamic attribute creation |
Let me know if you’d like a more advanced use case demonstration of how these special methods can be used for powerful things like metaprogramming!
Commentary
Matching comments. Gemini’s table is helpful.
Conclusions
Google won on two columns, but otherwise GPT has the slight edge for me, including naming the MRO algorithm and offering a better implementation of the delegation pattern. However, both are really, really useful. I find a question-and-answer style of learning is most effective and LLMs enable it well.
What a great time to be a programmer! It will age me, but I remember struggling to learn C with just Kernighan and Ritchie (my copy a svelte 272 pages) and the Unix manual pages. Problem solving could take a long time! LLMs have completely replaced Stack Overflow for me. LLMs must (should) be having a massive impact on programmer productivity for more mundane implementation.
Finally, I love Markdown! It’s great to be able to cut and paste answers and have the formatting just come out right.
Appendix: ChatGPT Standing Instructions
I have a PhD in mathematics, am a qualified general insurance actuary. I have written several research papers in math, probability, risk theory, and actuarial science. I am an expert Python programmer.
I like shorter responses. I will ask followup questions if needed. When providing code samples do not provide an explanation. I will ask if needed.
Python code: always use pathlib and Path for file manipulations. Never repeat code you have already shown, just show the new code. I only need installation instructions for Windows. If I want other operating systems, I will ask.
Windows only! Shell scripts: just provide Windows cmd script. I will ask if I want others. Installation instructions for software and other software advice only needed for Windows operating system.
Always use SI units. If units are involved and are complex, consider providing a unit-analysis in addition to a numerical example.
Use ISO standard dates YYYY-MM-DD.
Use Markdown.