Codewars中currying与partial函数实现问题求助

Hey there! Let's work through this problem you're having. The key issue with your current code is that when you nest curry_partial calls, you're trying to use inspect.signature on the wrapper functions (like g), which only tells you about the wrapper's parameters—not how many arguments the original function still needs.

Instead of relying on inspecting wrapped functions, we need to explicitly track two pieces of state for every call: the total number of arguments the original function requires, and the arguments we've collected so far. Here's a revised implementation that fixes this, plus a breakdown of how it works:

Revised Implementation #

from inspect import signature

def curry_partial(func, *initial_args):
    """Generates a curried/partial version of a function.
    Executes the function when enough arguments are provided, ignores extra args.
    """
    # Capture the total number of required parameters from the original function
    total_required = len(signature(func).parameters)
    # Track arguments we've collected so far
    collected = list(initial_args)

    def argument_collector(*new_args):
        nonlocal collected
        # Add new arguments to our collected list
        collected += list(new_args)
        
        # Check if we have enough arguments to run the original function
        if len(collected) >= total_required:
            # Pass only the number of args the function needs (ignore extras)
            return func(*collected[:total_required])
        
        # If not enough, return a new collector that carries forward our progress
        return curry_partial(func, *collected)
    
    # Edge case: if initial args already meet or exceed requirements, execute immediately
    if len(collected) >= total_required:
        return func(*collected[:total_required])
    
    return argument_collector

How This Fixes Your Nested Call Issue #

Let's walk through your test case to see what happens:
Suppose add is defined as:

def add(a, b, c):
    return a + b + c

When you call curry_partial(curry_partial(curry_partial(add, 1), 2), 3):

1. The innermost curry_partial(add, 1) collects [1], sees it's less than 3 required args, and returns a collector.
2. The middle curry_partial(<collector>, 2) doesn't inspect the collector's parameters—instead, it receives the original add function and the collected [1], adds 2 to get [1,2], and returns another collector.
3. The outermost curry_partial(<collector>, 3) adds 3 to get [1,2,3], which meets the total required args, so it executes add(1,2,3) and returns 6.

No more confusion between wrapper function parameters and the original function's needs!

Key Improvements Over Your Original Code #

• Explicit state tracking: We never lose sight of the original function's total required arguments, even through nested calls.
• No functools.partial limitations: By managing our own collected arguments instead of using partial, we avoid the problem of wrapped functions hiding the original function's signature.
• Flexible calling: This implementation supports all the call styles the problem requires:
  • curry_partial(add, 1)(2)(3) → 6
  • curry_partial(add)(1,2,3) →6
  • curry_partial(add, 1,2,3,4) →6 (ignores the extra 4)
  • curry_partial(add, 1,2)(3,4) →6 (ignores the extra 4)

Learning Tip for Currying/Partial Functions #

The core idea of both currying and partial application is argument collection over time. Instead of relying on language features that wrap functions (and hide their original details), focus on tracking the arguments you've gathered and comparing that to what the original function needs. This makes your implementation more transparent and less prone to edge cases like nested calls.

内容的提问来源于stack exchange，提问作者tobyvd