Python函数参数写法疑问：为何用location='princeton'而非'location'='princeton'

Hey there! Great question—this is such a common mix-up when you're new to Python, so let's break this down step by step.

First, let's clarify what location='princeton' actually is #

When you write location='princeton' in a function call like build_profile(..., location='princeton'), you're using a keyword argument. Here's what that means:

• location is the name of the parameter defined in the build_profile function (like def build_profile(name, location, ...):).
• Python uses this unquoted name to match the value directly to the correct parameter in the function definition. No quotes needed because it's referencing the parameter's identifier, not a string value.

Why 'location'='princeton' doesn't work #

If you wrap location in quotes, Python interprets 'location' as a string literal. In Python, you can't assign a value to a string—strings are immutable, and this syntax makes no sense to the interpreter. Try running that line, and you'll get a SyntaxError because Python sees you trying to set a string equal to something, which isn't allowed.

For example:

# This will throw an error!
build_profile('albert', 'location'='princeton')

The error message will look something like SyntaxError: expression cannot contain assignment, perhaps you meant "=="?—because Python thinks you might have confused assignment (=) with equality checking (==), but even that wouldn't make sense here.

A quick recap #

• Keyword arguments use the parameter's actual name (no quotes) followed by = and the value. This tells Python exactly which parameter your value should go to.
• Quoting the name turns it into a string, which can't be assigned to a value in this context—it's not a valid parameter reference.

Keep asking these detailed questions as you learn—they're a great sign you're paying attention to how Python's syntax works!

内容的提问来源于stack exchange，提问作者Daniel Scan