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title:
  - value: |
      PHP types and assertions
created:
  - value: '2023-08-20T00:00:00+00:00'
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  - value: '2025-05-11T09:00:34+00:00'
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      <p>Following yesterday's email about input validation, guard clauses and assertion libraries, these can be used to compliment PHP's native types and checking.</p>

      <p>For example:</p>

      <pre><code class="language-php">function createJourney(string $from, string $to, int $duration): void {
        var_dump($from, $to, $duration);
      }
      </code></pre>

      <p>In this code, each parameter has a type, but there's no validation on the values.</p>

      <p>If I run this:</p>

      <pre><code class="language-plain">createJourney('', '', -10);
      </code></pre>

      <p>I would get this output:</p>

      <pre><code class="language-plain">string(0) ""
      string(0) ""
      int(-10)
      </code></pre>

      <p>This is probably not what you want.</p>

      <p>I expect <code>$to</code> and <code>$from</code> to be not empty and the duration to be greater than zero.</p>

      <h2 id="here%27s-the-thing">Here's the thing</h2>

      <p>I can use an assertion library or throw my own Exceptions if the values pass the type checks but aren't what I need.</p>

      <p>For example:</p>

      <pre><code class="language-php">function createJourney(string $from, string $to, int $duration): void {
        Assert::stringNotEmpty($from);
        Assert::stringNotEmpty($to);
        Assert::positiveInteger($duration);

        var_dump($from, $to, $duration);
      }
      </code></pre>

      <p>Now, if an empty string or negative duration is passed - in my implementation or test code - an Exception will be thrown.</p>

              
    format: full_html
    processed: |
      <p>Following yesterday's email about input validation, guard clauses and assertion libraries, these can be used to compliment PHP's native types and checking.</p>

      <p>For example:</p>

      <pre><code class="language-php">function createJourney(string $from, string $to, int $duration): void {
        var_dump($from, $to, $duration);
      }
      </code></pre>

      <p>In this code, each parameter has a type, but there's no validation on the values.</p>

      <p>If I run this:</p>

      <pre><code class="language-plain">createJourney('', '', -10);
      </code></pre>

      <p>I would get this output:</p>

      <pre><code class="language-plain">string(0) ""
      string(0) ""
      int(-10)
      </code></pre>

      <p>This is probably not what you want.</p>

      <p>I expect <code>$to</code> and <code>$from</code> to be not empty and the duration to be greater than zero.</p>

      <h2 id="here%27s-the-thing">Here's the thing</h2>

      <p>I can use an assertion library or throw my own Exceptions if the values pass the type checks but aren't what I need.</p>

      <p>For example:</p>

      <pre><code class="language-php">function createJourney(string $from, string $to, int $duration): void {
        Assert::stringNotEmpty($from);
        Assert::stringNotEmpty($to);
        Assert::positiveInteger($duration);

        var_dump($from, $to, $duration);
      }
      </code></pre>

      <p>Now, if an empty string or negative duration is passed - in my implementation or test code - an Exception will be thrown.</p>

              
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