Aliasing a Method in Ruby Takes Simple Programming

Aliasing a Method in Ruby Takes Simple Programming To alias a method or variable name in Ruby is to create a second name for the method or variable. Aliasing can be used either to provide more expressive options to the programmer using the class or to help override methods and change the behavior of the class or object. Ruby provides this functionality with the alias and alias_method keywords. Create a Second Name The alias keyword takes two arguments: the old method name and the new method name. The method names should be passed as labels, as opposed to strings. Labels are used to refer to methods and variables without directly referencing them. If youre a new Ruby programmer, the concept of labels may seem odd, but whenever you see a label like :methodname, just read it as the thing called methodname. The following example declares a new class and creates an alias for the on method called start. #!/usr/bin/env rubyclass Microwavedef onputs The microwave is onendalias :start :onendm Microwave.newm.start # same as m.on Change the Behavior of a Class There may be times when you want to change the behavior of a class after its been declared. You can alias and add new methods to an existing class by creating second class declaration that has the same name as the existing class declaration. You can also add aliases and methods to individual objects using a syntax similar to the inherited class syntax. The behavior of any class can be changed by creating an alias for any method and then creating a new method (with the original method name) that calls the method with the alias. In the following example, a microwave class is declared and an instance is created. The second class declaration uses the alias method to change the behavior of the on method in order to add a warning message. The third class declaration is used to change the behavior of the specific microwave instance to add an even more stern warning. When aliasing a method multiple times, be sure to use different method names to store the old method. #!/usr/bin/env rubyclass Microwavedef on  Ã‚  Ã‚  Ã‚  puts Microwave is on  Ã‚  end endm Microwave.newm.onclass Microwave  Ã‚  alias :old_on1 :ondef on  Ã‚  Ã‚  Ã‚  puts Warning: Do not insert metal objects!  Ã‚  Ã‚  Ã‚  old_on1  Ã‚  end endm.on# Message for this specific microwaveclass   Ã‚  def onputs This microwave is weak, add extra timeold_on2endendm.on # Displays extra messagem2 Microwave.newm2.on # Does not display extra message

Free Essays on Endangered Species of South America

Endangered Species of South America Endangered species are plant and animal species that are in danger of extinction, the dying off of all individuals of a species. Over 19,000 plant species and 5000 animal species around the globe are classified as endangered, and many thousands more become extinct each year before biologists can identify them (Microsoft 1). The primary cause of species extinction or endangerment are habitat destruction, commercial exploitation, damage caused by non-native plants and animals introduced into an area, and pollution (1). Of these causes, direct habitat destruction threatens the most species. A steady rate of extinction is a normal process in the course of evolution, and is called the background rate of extinction (Lampton 14). Species have slowly evolved and disappeared throughout geological time because of climate changes and the inability to adapt to survive competition and predation. Since the 1600's, however, the rate of extinction has accelerated rapidly because of human population growth and resource consumption (17). Today, most of the world's habitats are changing faster than most species can adapt to such changes through evolution, or natural selection. The current global extinction rate is estimated at about 20,000 species per year, exponentially greater than the background extinction rate (17). Many biologists believe that we are in the middle of the greatest mass extinction episode since the disappearance of the dinosaurs 65 million years ago (18). The survival of ecosystems (plant and animal communities and their physical surroundings) such as forests, coral reefs, or wetlands depend on their biodiversity or variety of plants, animals, and habitats, as well as the many interactions among these species. The removal or disappearance of one or several species may irreversibly damage the ecosystems and lead to its decline. For example, the undersea kelp forest ecosystems ... Free Essays on Endangered Species of South America Free Essays on Endangered Species of South America Endangered Species of South America Endangered species are plant and animal species that are in danger of extinction, the dying off of all individuals of a species. Over 19,000 plant species and 5000 animal species around the globe are classified as endangered, and many thousands more become extinct each year before biologists can identify them (Microsoft 1). The primary cause of species extinction or endangerment are habitat destruction, commercial exploitation, damage caused by non-native plants and animals introduced into an area, and pollution (1). Of these causes, direct habitat destruction threatens the most species. A steady rate of extinction is a normal process in the course of evolution, and is called the background rate of extinction (Lampton 14). Species have slowly evolved and disappeared throughout geological time because of climate changes and the inability to adapt to survive competition and predation. Since the 1600's, however, the rate of extinction has accelerated rapidly because of human population growth and resource consumption (17). Today, most of the world's habitats are changing faster than most species can adapt to such changes through evolution, or natural selection. The current global extinction rate is estimated at about 20,000 species per year, exponentially greater than the background extinction rate (17). Many biologists believe that we are in the middle of the greatest mass extinction episode since the disappearance of the dinosaurs 65 million years ago (18). The survival of ecosystems (plant and animal communities and their physical surroundings) such as forests, coral reefs, or wetlands depend on their biodiversity or variety of plants, animals, and habitats, as well as the many interactions among these species. The removal or disappearance of one or several species may irreversibly damage the ecosystems and lead to its decline. For example, the undersea kelp forest ecosystems ...

Chinese Movie review Essay Example | Topics and Well Written Essays - 500 words

Chinese Movie review - Essay Example , the movie follows the story of a crime lord (Tang) in Shanghai during in the1930s and his singer mistress (Xiao Jingbao) as revealed gradually by their new boy servant (Shuisheng). The boy servant provides the point of view in the movies, often detailing the dynamics off the relationship between the powerful triad boss and his unpredictable mistress. In all aspects, crime is involved in acquiring power and making it in life. Shuiseng uncle (also a city criminal) is the one that links him up with the opportunity to work for the triad boss after getting him from the countryside. In the cause of working for the crime boss, he becomes accustomed to the happenings of the crime world such as seeing executions, hearing disturbing conversations and noticing the struggles of eth boss in making his mistress conform to his will. This gangster movie plotline presents the crime scene in Shanghai during the early years but fails to bring something unique to the audience. The viewers are likely t o see it as pointless and repetitive when they compare the film with other works in the gangster Chinese movies. The movie was made after the Chinese authorities ensured that there was no external funding. Production would only go ahead after falling under the local production category. This means that the movie was funded locally. This was an effort to ensure that the external sources did not influence the plot to paint a bad image of the Chinese authorities in its communist ways. Though there is no heavy use of stereotypes, the film nevertheless alludes to a particular political message that concerns the nature of the pre-revolutionary Shanghai and China in general. It depicts the lawlessness that was in China at the time rendering crime as a way to active power and stakes a claim in the society. Zhang Yimou manages to insert the social effect the criminal underworld and point to the larger problem in the Chinese society. The Forbidden Kingdom is presumably targeted for the U.S