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What's up geeks and welcome to the channel! If you're in the computer science domain you definitely have heard of design patterns before or even used a few patterns in practice with or without your knowledge but really what are design patterns?
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why were they created in the first  place and who decided to create them?
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what is actually the main  purpose behind design patterns?
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all these questions and more will be answered  in this first video of our design pattern series to which later we will add more videos  detailing each pattern on its own.
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As always and to better understand  the concept at hand let's take a practical example and let's imagine a steak. You see I may have imagined a well done steak you may have imagined a medium done one someone else might have imagined a vegan steak, while ordering a steak at a restaurant,  each one of us orders it differently we don't all necessarily have to  order or eat our steak the same way and yet the cook that is preparing it, will take the same piece of  meat or soy in addition to the way or policy of how we like our steak and prepare a delicious meal a different one for each one of us using the same  piece of meat as a starting point To compare this to a computer program suppose  we have a Chef class with a prepare() method This method can take a WellDoneInstruction  object and in this prepare method the chef will know how to prepare a well-done steak but what about other ways of preparing a steak we will have to overload this method to take in  a MediumDoneInstruction and a VeganInstruction Okay now our chef knows how  to cook all the steaks we want Let's say this chef extended his knowledge and  now knows of five additional ways to cook a steak should we add five more methods? Well let me suggest something else, why not replace all these methods with a single  method that takes a steak cooking instruction and let all these classes inherit  this one what do you think?
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Isn't that a better design for our Chef class You see this way, our class is closed  for modification and open for extension which means that not only we won't  have to add any more methods nor even touch our Chef class in the future but in addition to this when a new instruction is needed all we have to do is extend the SteakCookingInstruction class  we created with this new instruction and the prepare method will  handle it automatically Now because of our design, this chef  apparently skyrocketed and decided to open a new branch for the restaurant So every time a new customer enters the restaurant the chef goes ahead and informs them  of the opening date and details for the new branch but do you think that is the best  approach to deal with such a scenario?
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Don't you think that instead of  waiting for people to come in the chef should have instead messaged  all his customers the details about the opening or even posted on social media and those interested would have showed up wouldn't his reach be far larger? In both previous scenarios the solutions I suggested hint at a specific pattern this pattern will not actually solve our problem and generate magically ready code for us but rather it will give us a description or template to follow a way of thinking  that will help us solve these problems like a series of formalized best practices, steps  that programmers have followed and used to solve common problems like the one we just encountered. Design Patterns best became known from the design patterns book by Erich Gamma, Richard  Helm, Ralph Johnson, and John Vlissides often referred to as the Gang of  Four book published in the mid 90s.
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Now, this book details 23 design patterns  which were split into three groups: Creational Patterns, Structural  Patterns, and Behavioral Patterns.
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Creational patterns deal  with the creation of objects Instead of you instantiating all  objects very specifically and explicitly they give you more flexibility  in how the objects are actually created Let's suppose that we have  a class with 10 attributes but not every time we create an object based on  this class we need to specify all 10 attributes sometimes you only need one, in other cases  three or two, and sometimes eight or nine, in such cases we are left with two  solutions and not quite the best out there: either to create a lot, like a lot, of  overloaded constructors for our class or create one constructor that takes  all arguments but then we will need to pass as null values the ones we don't  require upon creation of our objects Well, design patterns will tell  you wait, you have a third option follow the template provided  by the Builder Pattern, a template widely used and tested  by many developers out there Well if I were in your shoes  I'd pick this last option.
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Structural patterns deal with  how classes are actually designed with how things like inheritance  and composition and aggregation can be used to provide extra functionality Let's consider that in our application we are storing book objects and these books well there's too many of them, like in the hundred thousand books of a library, or the books in all of amazon online store, and for some reason we need to represent each book by an object You see in this case we will have a bunch of book objects that will share the same attributes and by bunch I mean in the thousands which will have the same author, the same amazon  physical storage location, same places it can be delivered to, same provider, etc. you got the idea and maybe the only attribute that will defer is the title itself and the price in some cases So why create for each book an object and consume all this amount of memory while at the same time if we follow the template specified by the Flyweight Pattern we will be able to minimize memory usage by sharing as much data as possible  between our similar objects You see that is what design  patterns are trying to do they are trying to provide us with a schema, a step-by-step definition or template to help us overcome development or architectural  problems that others have faced before us.
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Finally, Behavioral patterns are specifically  concerned with communication and assignment of responsibilities between  objects as the program is running The two examples we gave at the beginning  of our video can actually be solved using two different behavioral patterns one of them being the Strategy pattern Let's take a second example and  suppose we realized that the state of an object in our application will  be changed by a lot of other objects but we need to be able to undo the last change Well this can be done in many different ways and you are free to use any of them but there is a Memento design pattern that describes a simple proven approach. So to sum up, design patterns will speed up your development process by providing  tested and proven development models At first you may not notice that you require  the use of this pattern here or there or you may make use of it without even knowing but with time practice and hopefully with the help of our videos you will! So that's it for this video, I hope it was helpful, thank you guys for watching,  take care and I will see you in the next one!

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Vocabulário e dicas de fala para esta lição

Esta aula de conversação de nível C1 usa o vídeo “What are Design Patterns?”. As palavras que mais se repetem: pattern, object, design, steak, chef. Este vídeo tem 11 frases e 1284 palavras para praticar shadowing. A fala dura 7:17. O falante fala em ritmo natural, cerca de 176 palavras por minuto, próximo de uma conversa do dia a dia. 85% das palavras estão entre as 3.000 mais comuns do inglês; vale a pena estudar o restante antes de começar. 7 das 11 frases são perguntas, por isso é um bom treino para a entonação de perguntas e respostas curtas.

Vocabulário principal deste vídeo

As 15 palavras mais avançadas do vídeo, com pronúncia e significado:

PalavraPronúnciaSignificado
steak substantivo/steɪk/bife
template substantivo/ˈtɛm.plɪt/modelo, predefinição
attribute substantivo/ˈæt.ɹɪˌbjut/atributo
behavioral adjetivo/bɪˈheɪvjəɹəl/comportamental
overload verbo/ˌəʊvəˈləʊd/sobrecarregar
specify verbo/ˈspɛs.əˌfaɪ/especificar
aggregation substantivo/æɡɹəˈɡeɪʃən/agregação
formalize verbo/ˈfɔɹ.məlaɪːz/formalizar
instantiate verbo/ɪnˈstænʃieɪt/instanciar
magically advérbio/ˈmæd͡ʒ.ɪ.kli/magicamente
skyrocket verbo/ˈskaɪˌɹɒk.ɪt/ir às alturas, elevar-se às alturas
inherit verbo/ɪnˈhɛɹɪt/herdar
programmer substantivo/ˈpɹoʊɡɹæmɚ/programador, programadora
undo verbo/ʌnˈduː/desfazer
geek substantivo/ɡiːk/geek

Phrasal verbs que você vai ouvir

PalavraPronúnciaSignificado
go ahead verbo/ˌɡoʊ əˈhɛd/vai em frente

Gramática neste vídeo

As estruturas que o falante mais usa, com as palavras exatas do vídeo:

EstruturaNo vídeo
Frases condicionais if + oração, will/would + verbo — uma condição e seu resultadoif I were in your shoes I'd pick
Voz passiva be + particípio passado — o foco está no que acontece, não em quem fazwill be answered · is closed · were split
Present perfect have/has + particípio passado — uma ação passada que ainda importa agorahave heard · have followed · have faced
Orações relativas who / which + oração — informação extra sobre uma pessoa ou coisaextension which means · patterns which were · thousands which will

Pronúncia para ficar de olho

O falante usa 8 contrações e formas reduzidas, como don't, I'd, isn't. Diga-as na forma curta, do jeito que você ouve.

  • Os sons de “sh” e “zh”: aggregation /æɡɹəˈɡeɪʃən/, instantiate /ɪnˈstænʃieɪt/, modification /ˌmɑdɪfɪˈkeɪʃən/
  • Palavras longas — acerte a sílaba tônica: behavioral /bɪˈheɪvjəɹəl/, aggregation /æɡɹəˈɡeɪʃən/, modification /ˌmɑdɪfɪˈkeɪʃən/, inheritance /ɪnˈhɛɹɪtəns/, architectural /ˌɑɹkɪˈtɛkt͡ʃəɹəl/

Sons difíceis para falantes de português:

  • Consoante final — sem acrescentar um “i” depois: steak /steɪk/, template /ˈtɛm.plɪt/, attribute /ˈæt.ɹɪˌbjut/, overload /ˌəʊvəˈləʊd/, instantiate /ɪnˈstænʃieɪt/
  • /l/ final — a língua toca o céu da boca, não vira “u”: behavioral /bɪˈheɪvjəɹəl/, null /nʌl/, architectural /ˌɑɹkɪˈtɛkt͡ʃəɹəl/
  • /h/ — um sopro suave, diferente do “r”: behavioral /bɪˈheɪvjəɹəl/, inherit /ɪnˈhɛɹɪt/, inheritance /ɪnˈhɛɹɪtəns/, hint /hɪnt/

Como praticar com este vídeo

  1. Ouça o vídeo inteiro uma vez sem falar e anote as palavras que você não conhece.
  2. Comece na velocidade 0,75×, faça shadowing frase por frase e volte à velocidade normal quando ficar fácil.
  3. Grave a sua voz e compare com o original, prestando atenção a palavras como steak, template, attribute.

O que é a Técnica de Shadowing?

Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.

Técnica de shadowing: leia o guia completo passo a passo →