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---
layout: post
title: "Hunting snakes with a shotgun"
description: "Python is a little too forgiving"
date: 2019-06-27 7:00:00
categories: random
---
A rather large number of people know me as "the guy who does weird things with python". I would object to this title, but it is quite accurate. So, here are some of the things I like playing with in python. None of these are actually breaking the language, just little known facts and syntax. At some point I will share about actually breaking the language. For now, enjoy the weird things I have found over the past 6 years.
## Type hints
A little known feature of python is called "type hinting" (PEP 484). This is actually quite common to see in standard libraries, and has it's own special syntax:
```python
# Here is a regular function
def meep(a, b):
return a*b^2
# This function has no real reason to exsist, and is lacking any sort of documentation.
# Let's add a docstring to explain what it does
def meep(a, b):
""" This function returns the result of a times b squared """
return a*b^2
# Ok. The docstring explains the function, but is not too helpful
# what are a and b? what does this return?
# For all we know, a could actually be a string (in which case, this function would return a string)
# Let's fix that up with a type hint
def meep(a: int, b: int):
""" This function returns the result of a times b squared """
return a*b^2
# Thanks to the :int (called a type hint in case you didn't notice that yet), we now know that this function expects two ints.
# Now, to finish this up with a secondary type hint to specify the return type
def meep(a: int, b: int) -> int:
""" This function returns the result of a times b squared """
return a*b^2
# There. Now we can clearly see that this function takes too ints, and returns one int.
# If only this was a requirement in the language. So many headaches could be solved.
```
Now, keep in mind that this is called a type *hint*. The python compiler (yes.. Give me a second for that one) does not actually care if you obey the hint or not. Feel free to send incorrect data into a hinted function and see what you can break. Critical functions should both hint and check the data types being provided.
## Type declarations
Just like type hints for functions, python has hints for variables too.
```python
# A regular variable. Must be declared with an initial value
my_state = None
# my_state is None, as it has not been set, but needs to exist.
# Let's assume that my_state is to be a state:
class State:
status = False
def toggle(self):
self.status != self.status
# Finally, its time to set the state to something useful
my_state = State()
my_state.toggle()
# Ok.. I hate this. Let's start by using type declarations first
# Any variable can be un-initialized and just have a type. Like so:
my_state: State
# This works for anything
is_alive: bool
age: int
name: str
# Now, with this new knowledge, let's rewrite State
class State:
status: bool
def toggle(self: State) -> None:
self.status != self.status
# And initialize my_state with slightly different syntax
my_state = State(status=True)
```
I have not found much use for this yet. Hopefully there is something cool to use it for.
## One-line functions
This is more common knowlage. A function can be declared in one line
```python
# Here is an adder function
def adder1(a:int, b:int) -> int:
return a+b
# Here is a one-line adder function
adder2 = lambda a,b : a+b
# State from above can be compacted further:
class State:
status: bool
toggle = lambda self: self.status != self.status
```
## Ternary operations
On the trend of one-line code, We have the one-line if/else, also known as a Ternary in more sensible languages.
```python
# Here is an if/else
if 100 is 5:
print("The world has ended")
else:
print("All is good")
# Here is a smaller if/else
print("The world has ended" if 100 is 5 else "All is good")
```
## Compiled python
This one is interesting. Python, like Java, is compiled into bytecode. So yes, it technically is a compiled language. To see said bytecode, take a look at any `.pyc` file sitting in your `__pycache__`
## Blog formatting experiments
I am still playing with post formats, and various types of content. This is more random than I usually prefer. Let me know your thoughts on the social media platform of your choosing.

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<?xml version="1.0" encoding="utf-8"?><feed xmlns="http://www.w3.org/2005/Atom" ><generator uri="https://jekyllrb.com/" version="3.8.5">Jekyll</generator><link href="http://localhost:4000/feed.xml" rel="self" type="application/atom+xml" /><link href="http://localhost:4000/" rel="alternate" type="text/html" /><updated>2019-06-26T16:54:25-04:00</updated><id>http://localhost:4000/feed.xml</id><title type="html">Evan Pratten</title><subtitle>Computer wizard, student, &lt;a href=&quot;https://github.com/frc5024&quot;&gt;@frc5024&lt;/a&gt; programming team lead, and radio enthusiast.</subtitle><entry><title type="html">BashSmash</title><link href="http://localhost:4000/random/2019/06/26/BashSmash.html" rel="alternate" type="text/html" title="BashSmash" /><published>2019-06-26T11:48:00-04:00</published><updated>2019-06-26T11:48:00-04:00</updated><id>http://localhost:4000/random/2019/06/26/BashSmash</id><content type="html" xml:base="http://localhost:4000/random/2019/06/26/BashSmash.html">&lt;p&gt;I was watching this great &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=2ahUKEwiOhNze_4fjAhUiB50JHR12D8AQwqsBMAB6BAgJEAQ&amp;amp;url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D6D1LnMj0Yt0&amp;amp;usg=AOvVaw2nOgft0SoPZujc9js9Vxhx&quot;&gt;Liveoverflow video&lt;/a&gt; yesterday, and really liked the idea of building escape sequences with strings. So, I built a new tool, &lt;a href=&quot;https://pypi.org/project/bashsmash/&quot;&gt;BashSmash&lt;/a&gt;.&lt;/p&gt;
<?xml version="1.0" encoding="utf-8"?><feed xmlns="http://www.w3.org/2005/Atom" ><generator uri="https://jekyllrb.com/" version="3.8.5">Jekyll</generator><link href="http://localhost:4000/feed.xml" rel="self" type="application/atom+xml" /><link href="http://localhost:4000/" rel="alternate" type="text/html" /><updated>2019-06-26T21:43:58-04:00</updated><id>http://localhost:4000/feed.xml</id><title type="html">Evan Pratten</title><subtitle>Computer wizard, student, &lt;a href=&quot;https://github.com/frc5024&quot;&gt;@frc5024&lt;/a&gt; programming team lead, and radio enthusiast.</subtitle><entry><title type="html">BashSmash</title><link href="http://localhost:4000/random/2019/06/26/BashSmash.html" rel="alternate" type="text/html" title="BashSmash" /><published>2019-06-26T11:48:00-04:00</published><updated>2019-06-26T11:48:00-04:00</updated><id>http://localhost:4000/random/2019/06/26/BashSmash</id><content type="html" xml:base="http://localhost:4000/random/2019/06/26/BashSmash.html">&lt;p&gt;I was watching this great &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=2ahUKEwiOhNze_4fjAhUiB50JHR12D8AQwqsBMAB6BAgJEAQ&amp;amp;url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D6D1LnMj0Yt0&amp;amp;usg=AOvVaw2nOgft0SoPZujc9js9Vxhx&quot;&gt;Liveoverflow video&lt;/a&gt; yesterday, and really liked the idea of building escape sequences with strings. So, I built a new tool, &lt;a href=&quot;https://pypi.org/project/bashsmash/&quot;&gt;BashSmash&lt;/a&gt;.&lt;/p&gt;
&lt;h2 id=&quot;the-goal&quot;&gt;The goal&lt;/h2&gt;
&lt;p&gt;The goal of BashSmash is very similar to that described in Liveoverflow’s video. Do anything in bash without using any letters or numbers except &lt;code class=&quot;highlighter-rouge&quot;&gt;n&lt;/code&gt; and &lt;code class=&quot;highlighter-rouge&quot;&gt;f&lt;/code&gt; (he used &lt;code class=&quot;highlighter-rouge&quot;&gt;i&lt;/code&gt; instead of &lt;code class=&quot;highlighter-rouge&quot;&gt;f&lt;/code&gt;). This can both bypass shell injection filters, and generally mess with people.&lt;/p&gt;