Industrial Strength Hash Table

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15 comments, last by swiftcoder 10 years, 1 month ago

I've been enjoying the coding horrors forum for a while, so I decided to post a snippet of code that I found in a large c++ project that I'm (unfortunately) a part of. Normally I wouldn't poke fun at code like this, but I couldn't resist this one.

Enjoy.


#pragma once

#include "Includes.h"



template<class T>

class Dictionary

{

private:

    std::vector<std::string> keys;

    std::vector<T> values;

public:

    Dictionary()

    {

        keys = new std::vector<std::string>{};

        values = new std::vector<T>{};

    }



    ~Dictionary()

    {

        delete[] keys;

        delete[] values;

    };



    std::vector* Values() { return &values; };

    std::vector* Keys() { return &keys; };



    size_t size() { return keys.size(); }



    void Add(std::string _key, T value)

    {

        keys.push_back(_key);

        values.push_back(value);

    };

    void Remove(std::string _key)

    {

        for (size_t i = 0; i < keys.size(); i++)

        {

            if (keys.at(i) == _key)

            {

                keys.erase(keys.begin() + i);

                values.erase(values.begin() + i);

                break;

            }

        }

    };

    T Get(std::string _key)

    {

        for (size_t i = 0; i < keys.size(); i++)

        {

            if (keys.at(i) == _key)

            {

                return values.at(i);

            }

        }

        return nullptr;

    };

};

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So let's see what the WTFs basically are...

  • Assigning a pointer generated from new to a type that is not a pointer
  • Using delete[] on objects created with new and not new[]
  • Using braces instead of brackets for trying to call the constructor of an object
  • Returning a pointer pointing to what is supposed to be an array of pointers pointing to pointers (given the new[] and delete[]), even though the value being returned isn't of type pointer (which is a double-WTF because if it were to compile, that would still be retarded)
  • using a lookup method of complexity O(n)
  • Attempting to declare a return type without template arguments.
  • Returning a nullptr in the case of not finding an entry, implying that the templated type is always a pointer.
  • Method names begin with a capital letter
  • not using std::map
  • code doesn't even compile

Evaluation:

tumblr_mc2w7cEoiz1qmiwbe.png

"I would try to find halo source code by bungie best fps engine ever created, u see why call of duty loses speed due to its detail." -- GettingNifty

#include "Includes.h"

Got to love the all encompassing include.


Method names begin with a capital letter

This one is excusable, since that is just personal preference. I personally don't like camelCase.

"I can't believe I'm defending logic to a turing machine." - Kent Woolworth [Other Space]

Yeah, my favorite is that the person is using std::Vector, but didn't bother to look for existing hash table functionality. Or maybe they did but their google fu sucks.

And I agree with Rattrap, the capital letter on method names is actually the coding guideline here at my work.

One also wonders why they didn't made a pair to use a single vector.

Want to talk about exception safety?

Previously "Krohm"

Does that code even compile? In what compiler?

Does that code even compile? In what compiler?

In every compiler.

As long as you don't use that template.


So let's see what the WTFs basically are...

I would add:

- Creating the std::vectors with new, where they would better be created on the stack. Its not like one of the vectors benefits is that it takes away the memory management for dynamic arrays.

- Returning both vectors as non-const pointer, basically breaking every concept of encapsulation of that class. Especially hard since both vectors are meant to store dependant values for one entry, imagine someone deleting values out of only the Value-vector.

- Also, returning the vectors by pointer instead of reference when they can never be nullptr.


Method names begin with a capital letter

Hey! What's wrong with this? rolleyes.gif

I would like to add one. How about every line being spaced with the beginning of each function being double spaced. That might be "personal" preference, but it is a hell of an annoying one.

Does that code even compile? In what compiler?

In every compiler.

As long as you don't use that template.

Hehehehe.

EDIT: Or the fact that every function is terminated with a semicolon. Again, personal preference; hell of an annoying one.

"The code you write when you learn a new language is shit.
You either already know that and you are wise, or you don’t realize it for many years and you are an idiot. Either way, your learning code is objectively shit." - L. Spiro

"This is called programming. The art of typing shit into an editor/IDE is not programming, it's basically data entry. The part that makes a programmer a programmer is their problem solving skills." - Serapth

"The 'friend' relationship in c++ is the tightest coupling you can give two objects. Friends can reach out and touch your privates." - frob

Does that code even compile? In what compiler?

In every compiler.

As long as you don't use that template.

Not instantiating a template doesn't prevent the first compilation pass, which will catch syntactical errors such as:


std::vector* Values() { return &values; }; // invalid use of template-name "std::vector" without an argument list
"I would try to find halo source code by bungie best fps engine ever created, u see why call of duty loses speed due to its detail." -- GettingNifty

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