Skip to main content

mastodon - Link to source

Still learning #Python. Whizzing through the lessons thinking "this is too easy." Then, of course, I sit down to write my first "real" program, an ASCII maze generator, and have to keep looking up things I already "learned." I also need to learn the type hints better.

gist.github.com/Ovid/6f67ebb40…


A simple ASCII maze program

A simple ASCII maze program. GitHub Gist: instantly share code, notes, and snippets.
Gist
#python
Unknown parent

Curtis "Ovid" Poe (he/him)
mastodon - Link to source
Curtis "Ovid" Poe (he/him)
• •

That prints out:

{'maze': <class '__main__.Maze'>, 'return': <class 'str'>}

So I guess I'm doing it right?

(And thanks for the kind words!)

This entry was edited (1 year ago)
in reply to Curtis "Ovid" Poe (he/him)

Füsilier Breitlinger
mastodon - Link to source
Füsilier Breitlinger
• •
Last time I looked at Python, the only way to get a local variable was to use string eval (which they spelled exec()). Do you know if that's still true?
in reply to Füsilier Breitlinger

bmaxv
mastodon - Link to source
bmaxv
• •

@barubary
"Get a local variable"? Not sure what you mean.

All variables are local and available in the function that they are defined in.

Global variables require the keyword but are bad practice.

@Füsilier Breitlinger
in reply to bmaxv

Füsilier Breitlinger
mastodon - Link to source
Füsilier Breitlinger
• •

@bmaxv @mdione @phiofx
By "local variable" I mean something that does not leak into or "pollute" the surrounding scope(s). Something like:

... regular code here ...<br>... tmp variable is not visible here ...<br># local scope starts here<br>tmp = Widget()<br>if tmp.foo():<br>    tmp.bar()<br># local scope ends here<br>... regular code here ...<br>... tmp variable is not visible here ...<br>

This is trivial in languages that let you declare local variables or provide local scopes, but in Python you cannot declare local variables and there are no local scopes, only entire functions.

You can try to fake a local scope by using a function (like the "IIFE" idiom in JavaScript), but that only moves the problem:

def local_scope_0():<br>    tmp = Widget()<br>    if tmp.foo():<br>        tmp.bar()<br>local_scope_0()<br>

The local variable is safely contained, but functions must be named in Python (OK, there are anonymous functions, but their bodies are limited to simple expressions), so now it is the function name that leaks into the surrounding scope. You still have to worry about name clashes and choosing unique identifiers, but this time for functions.

The only workaround I know is string eval:

exec('''<br>    tmp = Widget()<br>    if tmp.foo():<br>        tmp.bar()<br>''') # syntax might be off; it's been a while<br>

This ensures that there are no name clashes. tmp is safely contained in the exec() and won't clash with any identifier in the surrounding scope.
@bmaxv @Marcos Dione
in reply to Füsilier Breitlinger

bmaxv
mastodon - Link to source
bmaxv
• •

@barubary @mdione @phiofx the answer I would give is that it's incorrect to worry about these things *in Python*.

You are meant to put things into different functions or different classes or different files or different modules if you have to.

If this is a concern for the problem you are solving, python is the wrong tool for your problem.

@Füsilier Breitlinger @Marcos Dione
in reply to Füsilier Breitlinger

Marcos Dione
mastodon - Link to source
Marcos Dione
• •
@barubary all variables are local unless you declare them as nonlocal or global. do you have examples of what exactly do you mean by this?
@Füsilier Breitlinger
in reply to Curtis "Ovid" Poe (he/him)

Leandro Leites
mastodon - Link to source
Leandro Leites
• •
hey that is solid, I cannot think of any improvement :blobcatokhand:. I think types are fine, you can always check them with mypy or with the support from the IDE/editor you use. If you want to jump to the next level you can create a poetry project and add some pytest to it.
in reply to Leandro Leites

Curtis "Ovid" Poe (he/him)
mastodon - Link to source
Curtis "Ovid" Poe (he/him)
• •

@Lleites Poetry project? Never heard of that.

So far, the types are rather interesting. I have one type warning in create_maze() that I had to add a hint to ignore (can't figure out why it's wrong), but so far, it's pretty cool!

@Leandro Leites
in reply to Curtis "Ovid" Poe (he/him)

Leandro Leites
mastodon - Link to source
Leandro Leites
• •
Poetry is widely used as a Python project/dependency manager. Check the documentation that does a better job than me python-poetry.org/docs/

Introduction | Documentation | Poetry - Python dependency management and packaging made easy

Introduction Poetry is a tool for dependency management and packaging in Python. It allows you to declare the libraries your project depends on and it will manage (install/update) them for you.
python-poetry.org
⇧