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125 lines
4.9 KiB
125 lines
4.9 KiB
11 months ago
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<title>Julio Biason .Me 4.3</title>
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<link rel="stylesheet" href="https://blog.juliobiason.me/print.css" media="print">
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<div class="container sidebar-sticky">
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<div class="sidebar-about">
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<a href="https://blog.juliobiason.me"><h1>Julio Biason .Me 4.3</h1></a>
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<p class="lead">Old school dev living in a 2.0 dev world</p>
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</div>
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<ul class="sidebar-nav">
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<li class="sidebar-nav-item"><a href="/">English</a></li>
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<li class="sidebar-nav-item"><a href="/pt">Português</a></li>
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<li class="sidebar-nav-item"><a href="/tags">Tags (EN)</a></li>
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<li class="sidebar-nav-item"><a href="/pt/tags">Tags (PT)</a></li>
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</ul>
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<div class="content container">
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<div class="post">
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<h1 class="post-title">Things I Learnt The Hard Way - Not Just Function Composition, But Application Composition</h1>
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<span class="post-date">
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2019-07-15
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<a href="https://blog.juliobiason.me/tags/books/">#books</a>
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<a href="https://blog.juliobiason.me/tags/things-i-learnt/">#things i learnt</a>
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<a href="https://blog.juliobiason.me/tags/composition/">#composition</a>
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<a href="https://blog.juliobiason.me/tags/applications/">#applications</a>
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</span>
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<p>When we were discussing <a href="/books/things-i-learnt/magical-number-seven">the magical number
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seven</a>, I mentioned that it made
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more sense to actually call the functions in sequence instead of each calling
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the next. That's basically a "function composition", one thing you can also do
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with your applications.</p>
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<span id="continue-reading"></span>
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<p>Unix came with the idea of "applications that do one thing and do it well".
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And then you could just pick the output of one application and plug it as
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input of another (and then plug the output of the second into a third, and so
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on).</p>
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<p>Also, I mentioned that you could use <a href="/books/things-i-learnt/config-file">configuration
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files</a> to do the same processing over
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different source elements (based on a configuration, that is) instead of
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writing an application that would process both in a single shot.</p>
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<p>One problem with that approach is that you may need <em>both</em> results to actually
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produce a usable result (for example, how would you build a list of common
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followings of two Twitter users if you don't have both lists?).</p>
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<p>That problem can easily be solved if you write a different application that
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just receives both lists and compare them. That would greatly simplify your
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general codebase 'cause instead of one massive codebase with lots of moving
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pieces, you'd have two small codebases, with less moving pieces. One could
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still break the other -- say, if you or someone else changes the result of the
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first function -- but you will still get the results of the first without
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missing the whole 'cause the second is breaking.</p>
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<p>PS: I reckon it's really hard to create application composition with graphical
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applications (why would you ask your user to have <em>two</em> applications open at
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the same time to make something work?) but you can extrapolate this for almost
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everything else.</p>
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<div>
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<div style="float:left">
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<< <a href="/books/things-i-learnt/command-line-options">Command Line Options Are Weird, But Helpful</a>
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</div>
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<div style="float:right">
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<a href="/books/things-i-learnt/app-composition-stupid">Even for Application Composition, Start Stupid</a> >>
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</div>
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</div>
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</html>
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