Programming Languages
Play with local vars
Play with local vars
by Tatsuhiro UjihisaThe video titled 'Play with local vars' features a presentation by Tatsuhiro Ujihisa at RubyKaigi 2019, focusing exclusively on Ruby's local variables. The talk, lasting around 40 minutes, explores various aspects of local variables, including their behavior, pitfalls, and the dynamic nature of Ruby. Ujihisa begins with an engaging introduction, questioning the audience about their familiarity with local variables. Key points discussed include:
- Types of Variables: The presenter distinguishes local variables from other variable types in Ruby, such as global, instance, and class variables.
- Local Variables vs. Methods: Ujihisa emphasizes the intentional design of Ruby that blurs the line between local variables and methods, making them indistinguishable for users.
- Common Pitfalls: He warns about using 'eval' for dynamic code execution, illustrating a scenario where improperly declared local variables can lead to a NameError, as seen in the example using 'eval'.
- Using eval and Binding: The presentation covers the pitfalls of eval alongside the benefits of the Ruby binding method, which allows one to capture and manipulate local variable contexts effectively.
- Flexibility of Local Variables: Ujihisa shares that local variables can act as method parameters and are highly flexible within Ruby programming. He discusses how understanding these nuances contributes to effective Ruby development.
Throughout the talk, Ujihisa utilizes an interactive coding demonstration in Vim to illustrate his points, providing a real-time coding experience that enhances understanding. He concludes by reiterating the power and flexibility inherent in Ruby's handling of local variables and expresses eagerness for questions and deeper discussions. In summary, the talk serves as an insightful exploration into the dynamics of Ruby's local variables and their importance in programming practices.
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My talk is scheduled for six minutes, so while you're waiting, you can try running my code snippet without executing it.
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Are you ready to try? Great! Let's go.
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My concern today is that I have a sore throat, and when I practiced, it took about 17 minutes.
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I need to deliver the talk at a slower pace, but I'll do my best.
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So, I have a question: how many of you here have never used a local variable before?
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Raise your hand if you have never used a local variable.
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Okay, it seems that everyone has used local variables.
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Now, another question: do you fully understand local variables?
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If you completely understand local variables, that’s great.
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Here's a simple demonstration: Ruby allows you to write this kind of code.
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This is just five lines of Ruby code. Technically, two lines should be hidden for better complexity.
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What do you think the answer is? Just shout it out if you know.
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Does anybody want to take a guess?
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You're correct! Even with a warning, Ruby handles it.
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This code captures a continuation and returns a string.
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In this case, it returns a string with multiple values.
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Let's play around with local variables in theory; this was my talk.
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The abstract for my presentation, published on the RubyKaigi website, states that this presentation will occur mostly in Vim.
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That helps me work quickly, allowing me to demonstrate code snippets effectively.
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I'm currently using this empty buffer; watch as I type Ruby code and trigger it.
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I assign this to be a variable, and then I run commands.
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The process runs smoothly.
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Hello everyone, my name is Tatsuhiro Ujihisa.
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You can call me Woody.
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I'm here to share insights about Ruby.
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In the past, I have given talks, including a tiny talk in 2008 and 2009.
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Additionally, I spoke about various topics including Ruby and code structure.
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About two years ago, I discussed local variables in particular.
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This year, I am excited to present my first talk on Ruby's local variables.
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I am nervous but ready to share my experiences.
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Currently, I work at a company in Creper, creating Ruby on Rails applications.
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I've been involved in developing educational services using Ruby.
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The product I work on is mainly utilized in Indonesia, the Philippines, and Mexico.
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In Japan, we refer to it as Study Support.
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We are also hiring, so if any of you know anyone, please send them my way.
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I live part-time in Vancouver and Tokyo.
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One favorite feature of Ruby is its dynamic nature.
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There are many ways to declare and utilize local variables.
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My talk will focus on different aspects of Ruby and local variables.
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One of the simple ways is to assign values directly to variables.
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For example, if we assign 1, 2, and 3 to X, it will be straightforward.
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So, if you type X, it will reference the assigned values.
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We can also use local variables as method parameters.
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When calling a method with parameters, those parameters become local variables.
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In Ruby, there are several special local variable declarations.
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One common feature is using eval; everybody knows eval, right?
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With eval, you can execute Ruby code dynamically.
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However, keep in mind that using eval could lead to context issues.
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If you don't properly declare variables before calling them, it can raise a NameError.
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Thus, wrapping lines of code using eval has its potential pitfalls.
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The Ruby binding method allows you to capture the local variable context.
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Once captured, you can manipulate the binding context effectively.
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This is handy, as it provides access to local variables.
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In summary, this demonstrates the flexibility and potential complexity of Ruby's local variables.
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I found that understanding these nuances helps in effective Ruby programming.
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The dynamic nature of Ruby and its handling of local variables is a powerful feature.
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I look forward to your questions and discussions about these concepts.
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Thank you for your attention!
