In C++, all expressions have two properies: a type and a value category. Value categories are a little complicated to understand and have gone through a few changes with time.

lvalue and rvalue

Lvalue stands for locator value. An lvalue is something that occupies a memory location. But… doesn’t everything occupy a memory location? Not necessarily. Let’s look at a simple expression:

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int number = 7;

In this post I’m going to write about using exceptions for error handling in C++.

Exceptions

They are called exceptions, because they happen in exceptional scenarios. A program should in most cases run without exceptions, but sometimes unexpected things happen and we might want to do something in those scenarios.

Exceptions happen when there is either a developer error (Dereferencing a null pointer) or an environment error (Trying to write to a disk that is full). They should not happen for user triggered errors (incorrect input by user), if those errors are common.

When an error such as dereferencing a null pointer occurs, an Exception object is created. The Exception object contains information about the error, and the state of the program at the time this happened. The exception will then be thrown and left for the runtime to handle.

After installing a new distribution in my computer, I usually want to make some tweaks to gnome. In this post I’m going to explain how to do these tweaks from the command line, so they can be scripted.

gsettings

Gsettings is a command-line tools that allows us to modify gnome settings. To modify a setting we can use the set command. The format is like the following:

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gsettings set SCHEMA[:PATH] KEY VALUE

Ubuntu recently introduced snaps. Snaps are a new way of packaging applications in a way that there will be no dependency conflicts (because all dependencies are included). The only problem is that Ubuntu will create a snap folder in your home folder that you will most likely never need to access.

If you, like me, find this folder annoying, you can hide it from Nautilus:

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cd ~
echo snap >> ~/.hidden

This makes the folder invisible in Nautilus, but it will still be visible in other places (The terminal, for example).

I reinstalled Ubuntu on my personal computer recently and I noticed that there are some things I don’t like about the default distribution. One of the things I noticed is that Firefox keeps asking me if I want it to remember my passwords, which I don’t.

I know that I can go to settings and disable this feature, but I wanted to learn how to do it programmatically, so in the future I can just run a script and have Firefox work the way I want.

Preferences

There is documentation explaining how preferences work for mozilla projects, but it’s a little hard to understand how to exactly do what I wanted to do.

If you are not familiar with Inheritance, I recommend you read my short article about inheritance first.

One of the features of Object Oriented Programming is Polymorphism. Virtual functions in C++ allow developers to achieve run-time polymorphism by overwriting methods of a base class.

In my article about inheritance, I showed how we can create classes that inherit from a base (or parent) class. Something similar to the following:

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class Greeter {
 public:
  void talk() {
    std::cout << "hello" << std::endl;
  }
};

class SpanishGreeter : public Greeter {
 public:
  void talk() {
    std::cout << "hola" << std::endl;
  }
};

Inheritance is a feature of Object Oriented Programming that allows programmers to create classes based on other classes. A class that inherits from another class will have the same behavior as the parent class unless it is overwritten.

Let’s say we have a class:

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class Greeter {
 public:
  void talk() {
    std::cout << greeting_ << std::endl;
  }

 protected:
  std::string greeting_ = "hello";
};

Enumerations are useful when we want to have a custom type, that can only have a limited number of values. For example:

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enum Mode {
  EASY,
  MEDIUM,
  HARD
};

We can create variables of type enum that can only have one of the previously defined values:

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Mode userMode = EASY;

In this post I’m going to talk about the advantages of using std::array vs a c-style array whenever it is possible to do so.

C-style arrays

Let’s start by remembering what a c-style array is.

In C and C++ we can create an array of ints like this:

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int arr[3];

In a previous article I explained how to create a Conan package. In this article I’m going to show the steps needed to publish it, so it can be used by anyone.

After we have our Conan package ready, we need to create a JFrog Bintray account.