# Code Smell 77 - Timestamps

*Timestamps are widely used. They have a central issuing authority and do not go back, do they?*

> TL;DR: Don't use timestamps for sequence. Centralize and lock your issuer.

# Problems

- Bijection Fault.

- Timestamp Collisions.

- Timestamp precision.

- Packet Disorders.

- Bad [Accidental Implementation](https://maximilianocontieri.com/no-silver-bullet) (Timestamp) for an Essential Problem (Sequencing).

# Solutions

1. Use a centralizing sequential stamper. (NO, not a [Singleton](https://maximilianocontieri.com/singleton-the-root-of-all-evil)).

2. If you need to model a sequence, [model a sequence](https://maximilianocontieri.com/the-one-and-only-software-design-principle).

# Sample Code

## Wrong

[Gist Url]: # (https://gist.github.com/mcsee/395fe180085be252c2ff97020b9f3bc9)
```python
# using time module
import time
  
# ts stores the time in seconds
ts1 = time.time()
ts2 = time.time() #might be the same!!
```

## Right

[Gist Url]: # (https://gist.github.com/mcsee/67d4df804716d5fb10bcbb7d8ce6f7fe)
```python
numbers = range(1, 100000)
#create a sequence of numbers and use them with a hotspot

#or
sequence = nextNumber()

```

# Detection

Timestamps are very popular on many languages and are ubiquitous. 

We need to use them just to model... timestamps.

# Tags

- Bijection

# Conclusion

This smell was inspired by recent [Ingenuity software fault](https://www.hebergementwebs.com/transport/the-autonomous-helicopter-mars-named-ingenuity-is-confused-by-a-time-stamp-issue-providing-insightful-lessons-for-self-driving-cars-ai).

If we don't follow our [MAPPER](https://maximilianocontieri.com/the-one-and-only-software-design-principle) rules and model sequences with time, we will face trouble.

Luckily, Ingenuity is a sophisticated Autonomous vehicle and has a robust fail-safe landing software.

This video describes the glitch

%[https://www.youtube.com/watch?v=6IoMiwxL2wU]

# Relations

%[https://maximilianocontieri.com/code-smell-39-new-date]

%[https://maximilianocontieri.com/code-smell-32-singletons]

%[https://maximilianocontieri.com/code-smell-71-magic-floats-disguised-as-decimals]

# More info

- [Timestamp proposed changes](https://ieeexplore.ieee.org/document/805196)

- [Build a Mapper](https://maximilianocontieri.com/the-one-and-only-software-design-principle)

- [What is wrong with software](https://maximilianocontieri.com/what-is-wrong-with-software)

* * *

> The most beautiful code, the most beautiful functions, and the most beautiful programs are sometimes not there at all. 

_Jon Bentley_
 
%[https://maximilianocontieri.com/software-engineering-great-quotes]

* * *

This article is part of the CodeSmell Series.

%[https://maximilianocontieri.com/how-to-find-the-stinky-parts-of-your-code]