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Tech Talk: Code Modularization 31st August 2018 Taka

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What is Modularization for?

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To Make Good Software!

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What is Good Software?

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Good Software Meets Requirements!

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Good Software (in my opinion) ● “At least” needs to meet the business requirements ○ Software that doesn’t meet the requirements is rubbish ■ What if Twitter didn’t have the feature to tweet your thoughts... ● Should be extensible, maintainable, and reusable ○ Because...

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Why Extensibility / Maintainability / Reusability Matter?

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To Meet the Requirements!

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Business Requirements ● Business requirements frequently change ○ We may come up with a better idea 3 days after we decide something important ● New requirements constantly show up ○ We may want to launch a new service or feature instead of refining existing ones

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Software Needs Updating!

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Updating Software ● Software should be updated as quickly as possible ○ All of us want to deploy new features as soon as possible and ahead of competitors. ● Software should be as understandable as possible ○ The more your business grows, the more developers join you. It’s obvious that newcomers can easily catch up if the software is understandable.

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That’s Why We Make Much of Extensibility, Maintainability, and Reusability

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Again, What is Modularization for?

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Code Modularization Contributes to ● Maintainability ● Extensibility ● Reusability

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Code Modularization Contributes to Updating Software Easily, which Contributes to Providing Services That Meet the Requirements

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What If Requirements Never Change If we are 100% sure requirements won’t change forever and there is no need to maintain the software, extensibility, maintainability, and reusability don’t matter. It might be possible in some special occasions, but practically, it hardly ever happens when you are developing services.

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Example for Modularization

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Let’s Say You’re Building Software to Produce Pringles

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Before Doing Pringles... I’m going to use ‘mathematical-function-like-programs’. f(x) = y ● f: the name of the function (program) ● x: the parameter of the function (program) ● y: the result of the function (program) given ‘x’

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Example of a Function calculate_property_value(postcode, number_of_bath_rooms) ● Program name: calculate_property_value ● Parameters: postcode, number_of_bath_rooms ● Result: the value of the given information This program will calculate the property value based on the given postcode and the number of bath rooms.

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Simplified Processes of Production 1. Grow Potatoes 2. Cut Potatoes 3. Fry Potatoes 4. Season Potatoes 5. Pack Potatoes 6. Ship it!

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Simplified Processes of Production 1. Grow Potatoes 2. Cut Potatoes 3. Fry Potatoes 4. Season Potatoes 5. Pack Potatoes 6. Ship it! Let’s make a program to do these 4 steps!

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The Program to Make You can pass potatoes and this program will produce pringles! produce_pringles(potatoes) = a_pack_of_pringles ● Name: produce_pringles ● Parameters: (potatoes) ● Result: a pack of pringles

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Use Case of the Program 1. Jed cultivates potatoes 2. Nino receives potatoes from Jed and uses the ‘produce_pringles’ program 3. The ‘produce_pringles’ program produces Pringles 4. Nino sends Pringles to Taka 5. Taka enjoys Pringles!

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Usage of the Program As long as you have enough potatoes, you can produce as much as Pringles you want by using this program. If Nino has 100 units of potatoes (1 unit is for one pack of Pringles), Nino can get 100 packs of Pringles by calling ‘produce_pringles’ 100 times.

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Nino’s Job with and without the Program Without the Program 1. Cut potatoes 2. Fry potatoes 3. Season potatoes 4. Pack potatoes 5. Ship it With the program 1. Use the program 2. Ship it

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No content

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A New requirement is coming...

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Nino produces normal Pringles, but Taka wants beer-flavored one.

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Nino needs a new program!

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Details of the Current Program What is happening inside the program is: ● Cut potatoes ● Fry potatoes ● Season potatoes <= Using only salt right now ● Pack potatoes

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First Solution (Non-modularized) produce_pringles_beer_flavored(potatoes) ● Name: produce_pringles_beer_flavord ● Parameter: potatoes ● Result: Beer flavored Pringles

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Comparison between two programs produce_pringles 1. Cut potatoes 2. Fry potatoes 3. Season potatoes with salt 4. Pack potatoes produce_pringles_beer_flavord 1. Cut potatoes 2. Fry potatoes 3. Season potatoes with beer 4. Pack potatoes

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Closer look at Cut Potatoes I haven’t told it, but cutting potatoes consists of 10 steps. 1. Wash potatoes 2. Peel potatoes 3. etc.

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More Realistic Details of Two Programs produce_pringles 1. Cut potatoes (10 steps) a. Wash potatoes b. Peel potatoes c. And so on... 2. Fry potatoes (5 steps) 3. Season potatoes with salt (12 steps) 4. Pack potatoes (3 steps) produce_pringles_beer_flavord 1. Cut potatoes (10 steps) a. Wash potatoes b. Peel potatoes c. And so on... 2. Fry potatoes (5 steps) 3. Season potatoes with beer (12 steps) 4. Pack potatoes (3 steps)

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The regulation of washing potatoes has changed! You need to update your software to follow the new law!

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Updated Two programs produce_pringles 1. Cut potatoes (10 steps) a. Wash potatoes b. Sanitize potatoes c. Peel potatoes d. And so on... 2. Fry potatoes (5 steps) 3. Season potatoes with salt (12 steps) 4. Pack potatoes (3 steps) produce_pringles_beer_flavord 1. Cut potatoes (10 steps) a. Wash potatoes b. Sanitize potatoes c. Peel potatoes d. And so on... 2. Fry potatoes (5 steps) 3. Season potatoes with beer (12 steps) 4. Pack potatoes (3 steps)

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Let’s make new programs (modules)!

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New programs (modules) ● cut_potatoes(potatoes) ● fry_potatoes(potatoes) ● season_potatoes(potatoes, flavor) ● pack_potatoes(potatoes)

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Updated Programs with new modules produce_pringles 1. cut_potatoes(potatoes) 2. fly_potatoes(potatoes) 3. season_potatoes(potatoes, salt) 4. pack_potatoes(potatoes) produce_pringles_beer_flavord 1. cut_potatoes(potatoes) 2. fry_potatoes(potatoes) 3. season_potatoes(potatoes, beer) 4. pack_potatoes(potatoes) To cope with the new potato law, you no longer need to modify two places. Instead, you just need to update the ‘cut_potatoes(potatoes)’ program!

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Look for similarity for further abstraction produce_pringles 1. cut_potatoes(potatoes) 2. fly_potatoes(potatoes) 3. season_potatoes(potatoes, salt) 4. pack_potatoes(potatoes) produce_pringles_beer_flavord 1. cut_potatoes(potatoes) 2. fry_potatoes(potatoes) 3. season_potatoes(potatoes, beer) 4. pack_potatoes(potatoes) Most parts of both programs are pretty much the same! You may make a new program that is more reusable!

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More Reusable Program ● Old ○ produce_pringles(potatoes) ○ produce_pringles_beer_flavord(potatoes) ● New ○ produce_pringles(potatoes, flavor)

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Benefits of the new one ● You only need to maintain only one program, instead of two ● You don’t need to create a new program to produce a new flavored Pringles

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You got more extensible, maintainable, and reusable program!

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Our modules for websites https://www.immo.co.uk/styleguide

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Summary ● Code Modularization is for ○ Maintainability ○ Extensibility ○ Reusability ■ Each of which is for updating software to meet the requirements

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Thanks a million!