All junior devs should read OCs comment and really think about this.

The issue is whether is_number() is performing a semantic language matter or checking whether the text input can be converted by the program to a number type.

The former case - the semantic language test - is useful for chat based interactions, analysis of text (and ancient text - I love the cuneiform btw) and similar. In this mode, some applications don’t even have to be able to convert the text into eg binary (a ‘gazillion’ of something is quantifying it, but vaguely)

The latter case (validating input) is useful where the input is controlled and users are supposed to enter numbers using a limited part of a standard keyboard. Clay tablets and triangular sticks are strictly excluded from this interface.

Another example might be is_address(). Which of these are addresses? ‘10 Downing Street, London’, ‘193.168.1.1’, ‘Gettysberg’, ‘Sir/Madam’.

To me this highlights that code is a lot less reusable between different projects/apps than it at first appears.

Surely that is reserved for QA!

This is exactly the answer.

I’d just expand on one thing: many systems have multiple apps that need to run at the same time. Each app has its own dependencies, sometimes requiring a specific version of a library.

In this situation, it’s very easy for one app to need v1 of MyCleverLibrary (and fails with v2) and another needs v2 (and fails with v1). And then at the next OS update, the distro updates to v2.5 and breaks everything.

In this situation, before containers, you will be stuck, or have some difficult workrounds including different LD_LIBRARY_PATH settings that then break at the next update.

Using containers, each app has its own libraries at the correct and tested versions. These subtle interdependencies are eliminated and packages ‘just work’.

Not really. People shed skin and hair constantly, and the small particles float in the air and distribute themselves throughout the volume. And your bacteria are along for the ride. One of the functions of the protective suits, gloves and hairnets is to contain these these particles and thus keep the air as clean as possible. When combined with lamina airflow, positive room pressure and other techniques, it keeps contamination down hugely.

In other words, a ROOAALTA.

Here’s a video with a lot of guidance and examples of use: https://youtu.be/EAQI2ZSmxPU?si=lF5xr8fKyCRHEk7F