Mastodawn

Trey Hunner 🐍15h ago

“Quacking is quacking, and when it comes to iterables, looping is looping.”

#Python

All iteration is the same in Python

In Python, for loops, list comprehensions, tuple unpacking, and * unpacking all use the same iteration mechanism.

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Trey Hunner 🐍17h ago

So a list-of-lists is really a list of references to lists.

The shorthand of thinking of one object as "contained" in another is often helpful, but there is no real "containment" of one object within another in Python.

Most Python gotchas are related to EITHER the pointer nature of variables OR the pointer nature of objects.

So thinking in terms of pointers, for both VARIABLES and OBJECTS will help you avoid most gotchas before the getcha.

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Trey Hunner 🐍17h ago

Python Tip #86 (of 365):

Acknowledge that containment is (sort of) a lie.

Data structures in Python don't contain data...

Well, at least data structures don't contain objects.

Variables don't contain objects: they just point to them.

Likewise, data structures, and all other objects ALSO don't contain objects.

Data structures only POINT to objects.

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#Python #DailyPythonTip

Trey Hunner 🐍1d ago

jacobian 1d ago

I do believe that people can change, and that there can (and should) be a path back to good standing in a community.

But that path needs to involve taking ownership of the harm they caused — even if, heck especially if, they’re no longer a person who would do those things. And they need to at least attempt to make amends in some way.

Without these things, I’m not going to be able to assume good intentions of someone trying to come back.

Trey Hunner 🐍1d ago

Python Tip #85 (of 365):

Think of variables as pointers.

When explaining your code in Python, be sure to disambiguate between the 2 types of change (assignments and mutations).

"Changing" a variable just changes which object that variable points to.

"Changing" an object mutates that object. Every reference to that object will "see" the change.

Many Python gotchas derive from the pointer nature of Python's variables.

https://pym.dev/2-types-change/

#Python #DailyPythonTip

Assignment vs. Mutation in Python

In Python, "change" can mean two different things. Assignment changes which object a variable points to. Mutation, changes the object itself.

Trey Hunner 🐍1d ago

“It's also printing out the programmer-readable representation instead of the human-readable one, which makes it a little bit clearer that answer is currently a string, but it's supposed to be a number.”

#Python

Debugging with f-strings

If you're debugging Python code with print calls, consider using f-strings with self-documenting expressions to make your debugging a little bit easier.

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Trey Hunner 🐍2d ago

For example, it may not be clear what this condition checks:

if len(text) - len(text.lstrip()) >= 4:
...

But it's pretty clear what this one checks:

indent_level = len(text) - len(text.lstrip())
if indent_level >= 4:
...

Even if a variable is strictly unnecessary, if it improves readability you should keep it!

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Trey Hunner 🐍2d ago

Python Tip #84 (of 365):

Use variables to improve code clarity.

Today's tip is the inverse of yesterday's tip.

Well-named variables CAN make your code more readable and they don't really make your code less efficient (after all, variables are just pointers).

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#Python #DailyPythonTip

Trey Hunner 🐍2d ago

“Any function or class that accepts an iterable can accept a generator expression.”

#Python

Invent your own comprehensions in Python

Python doesn't have tuple, frozenset, or Counter comprehensions, but you can invent your own by passing a generator expression to any iterable-accepting callable.

Trey Hunner 🐍2d ago

Ned Batchelder 3d ago

Python tip: when you need to show something, repr() goes to nerds, str() goes to normies.

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