Debugging para el no iniciado

De Frustrado a Competente
Debugging para el no iniciado:
Barcamp 2015, Santiago, R.D.

What we will cover
- What is debugging
- Why is hard
- Know yourself
- The true path to debugging
- The rules of debugging
- What debugging displays
- Remember

About me
Leonardo Jimenez (Un entusiasta del software)
Blog: www.leonardo.do
correo: leonardo@codetiger.co
Co-Founder and Developer @Codetiger
We love Python, We use a ton of stuff
One of the organizers of @pythondo && @Jsdo

Can you tell me what debugging means to you?
What is debugging?

What is debugging?
Can you tell me what debugging means to you?
Some frequent answers:
- Make the error go away
- Eliminate the errors on the screen
- “Resolver…!”

What is debugging?
Most of the answers are related to fixing the actual
problem ...

What is debugging?
My (really recent definition) Definition
“Debugging is the process of finding and resolving bugs or
defects in the code in a manner that the code is better than
the way it was found”

What is debugging?
Debugging Normally includes:
1. Get the bug in the database (if you are lucky)
2. Reproduce the problem
3. Automate and simplify the test case (if you know what you
are doing)
4. Find possible infection origins
5. Focus on the most likely origins
6. Isolate the infection chain
7. Correct the defect

What is debugging?
are doing)
{
Understand the Problem

What is debugging?
are doing)
{
Search the Problem

What is debugging?
are doing)
7. Correct the defect{
Fixing it

What is debugging?
are doing)
{
Most of your time goes here

Why is debugging hard?
Key Takeaway #1
Debugging is a problem of scarcity

Let’s do an exercise:
- Search on Google “Learn to Program”

Let’s do an exercise:
- Search on Google “Learn to Program”
- 1,540,000,000 Results (1.5 Billion results)

Let’s do another exercise:
- Search on Google “Implement an
ordered List”
- 3,020,000 Results

Let’s do another exercise:
- Search on Google “Ordered Hash Table”
- 758,000 Results

The more advanced your question is,
the less easy answers you will find

Do you remember your first time?

Do you remember your first time?
print “Hello world”

Do you remember your first CRUD App?
Your first blog?, your first to do list?
What do they have in common?

Do you remember your first CRUD App?
Your first blog?, your first to do list?
What do they have in common?
You knew the whole App!!!

This is what it feels like working on a new,
different and legacy codebase ...

The difference between a good developer
and a bad developer is understanding.

The difference between a good developer
and a bad developer is understanding.
Understanding of what does not change.

Know yourself
Do you understand the basics of your
(Language/Library/framework) or you just
did a tutorial?

Know yourself
Do you read the documentation while
learning the technology or after something’s
break?

Know yourself
Do you know the standard library well or
you just copy/paste from stack overflow?

Know yourself

Know yourself (example)
def is_equal(a, b):
return a is b
>> is_equal(2, 2)
True
>> is_equal(4, 3)
False

def is_equal(a, b):
return a is b
>> value = 256
>> is_equal(256, value)
?

def is_equal(a, b):
return a is b
>> value = 256
True

def is_equal(a, b):
return a is b
>> value = 257
?

def is_equal(a, b):
return a is b
>> value = 257
False

def is_equal(a, b):
return a is b
Why???

def is_equal(a, b):
return a is b
Equality is different to Identity

In General
Key Takeaway #2
The code can give you the right result for
the wrong reasons.

Ruby Example

class Bicycle
attr_reader :size, :parts
def initialize(args={})
@size = args[:size]
@parts = args[:parts]
end
def spares
parts.spares
end
end

class Parts < Array
def size
parts.size
end
end

class Part
attr_reader :name, :description, :needs_space
def initialize(args)
@name = args[:name]
@description = args[:description]
@needs_spare = args.fetch(:needs_spare, true)
end
end

# Individual Parts
chain = Part.new(name: 'chain', description: '10-speed')
road_tire = Part.new(name: 'tire_size', description: '23')
tape = Part.new(name: 'tape_color', description: 'red')
mountain_tire = Part.new(name: 'tire_size', description: '2.1')
rear_shock = Part.new(name: 'rear_shock', description: 'Fox')
front_shock = Part.new(
name: 'front_shock',
description: 'Manitou',
needs_spare: false)

# Parts Objects
road_bike_parts = Parts.new([chain, road_tire, tape])
mountain_bike_parts = Parts.new([chain, mountain_tire,
front_shock, rear_shock])

# Bicycle Objects
road_bike = Bicycle.new(size: ‘L’, parts: road_bike_parts)
mountain_bike = Bicycle.new(size: ‘L’, parts:
mountain_bike_parts)

# Property Tests
mountain_bike .size # - > ‘L’
mountain_bike.spares
# - > [#<Part:0x00000101036770
# @name="chain",
# @description="10-speed",
# @needs_spare=true>,
# #<Part:0x0000010101b678
# @name="tire_size",
# etc ...

# Property Tests
combo_parts =
(mountain_bike.parts + road_bike.parts)
combo_parts.size # - > 7
combo_parts.spares
# - > NoMethodError: undefined method 'spares'
# for #<Array:...>

# Property Tests
combo_parts =
(mountain_bike.parts + road_bike.parts)
combo_parts.size # - > 7
combo_parts.spares
# - > NoMethodError: undefined method 'spares'
# for #<Array:...>
Why?

In General
The code can give you the right result for
the wrong reasons.

The True Path to Debugging

In General
Key Takeaway #3
Growing as a software developer means
moving from memorisation to understanding

In General
Key Takeaway #4
Avoid shotgun surgery become a neurosurgeon.

- Know Yourself tools
- Search within your code
- Be one with the universe person who asks

(You can Name it)
ARE
TOOLS

LEARN:
- When to use it and when not
- Learn Many and avoid a lot more
- One really well
- Learn the principles

In General
Key Takeaway #5
Debugging is not a tool, is a mindset.
The mindset name is curiosity.
Be Curious.

READ THE $#%@$%# MANUAL:
- Read the documentation
- Read the specifications
- Read the code (yes, for Fun)

If Nothing else works ask, but:
- Make sure you read the documentation
- Make your homework
- Tried to solve it yourself

When asking:
- Be respectful
- Tell the facts not your theories
- Don’t be proud

Debugging Rules
- Understand the system
- Make it Fail
- Quit Thinking and look
- Divide and conquer
- Change one thing at a time
- Keep up an audit trail
- Check if it is on
- Talk with another person
- If you don't fix it, it ain't fixed

Remember?
Do you remember the definition of Debugging?

Remember?
Does every interaction with your code making it better?

Remember?
Or do you sing ?
99 little bugs in the code
Take one down, patch it around

In General
Key Takeaway #6
In order to be an amazing debugger you
should be an incredible refactorer.

In the end
- Don’t rush
- Don’t Panic
- Understand the problem
- Understand your Language
- Understand your tools
- RTFM
In General

Preguntas??
Debugging para el no iniciado:

Gracias !!
Blog: www.leonardo.do
correo: leonardo@codetiger.co
twitter: @leonardoajim

Debugging para el no iniciado

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