Add daily email for 2024-01-18

Is zero unlimited?

source/_daily_emails/2024-01-18.md

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+---
+title: Is zero unlimited?
+date: 2024-01-18
+permalink: archive/2024/01/18/is-zero-unlimited
+snippet: |
+  If you set a limit to be zero, would you expect it to return all the results or none?
+tags:
+  - software-development
+  - clean-code
+---
+
+Something I've seen in code is the unclear use of zero when adding limits, such as loading items from a database.
+
+In some instances, setting zero will return all items - essentially, an 'unlimited' value in disguise - rather than returning no results, which is what I'd expect.
+
+I imagine the code looks something like this:
+
+```php
+if ($limit > 0) {
+  $query->range(0, $limit);
+}
+```
+
+If `$limit` is greater than one, add it to the query.
+
+For me, using `0` as the unlimited value doesn't seem like the best option.
+
+I'd prefer to use a `null` value as the default and only add the limit if it's set - i.e. an integer or not null.
+
+It means the value could be either an integer or null, but I think the intent of the code is more explicit.
+
+This would make the code look like this:
+
+```php
+if (is_int($limit)) {
+  $query->range(0, $limit);
+}
+```
+
+Whilst this is clearer, it doesn't cover all use cases.
+
+Presumably, the limit should only be a positive integer.
+
+It wouldn't make sense to set a negative number as the limit or, as the unlimited value is `null`, setting it to zero.
+
+This is the end code I'd likely write:
+
+```php
+if (is_int($limit)) {
+  if ($limit < 1) {
+    throw new InvalidArgumentException('A limit must be a positive integer.');
+  }
+
+  $query->range(0, $limit);
+}
+```
+
+If the limit is not an integer, nothing happens.
+
+It throws an Exception if the value is invalid - i.e. less than one.
+
+The limit is applied if the limit is greater than or equal to one.
+
+While it's more complex as there are more checks to perform and different types in use, I think this is clearer and easier for someone reading or implementing the code to understand what it does and use it correctly.