# Nomnoml

Nomnoml draws class-style UML from a very small syntax: names in brackets, arrows between them. It has a distinctive look and gets out of the way.

It suits sketching a class model quickly, where full UML would slow you down.

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## What it is good at

* Quick class and package sketches during design.
* Teaching material where the syntax should not be a distraction.
* Diagrams embedded in code comments and READMEs.

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## What it draws

| **Diagram**  | **Syntax starts with**         |
| ------------ | ------------------------------ |
| Class        | \[ClassName\]                  |
| Association  | \[A\] -> \[B\]                 |
| Inheritance  | \[A\] <:- \[B\]                |
| Composition  | \[A\] +-> \[B\]                |
| Compartments | \[Name\|field;field|method()\] |
| Directives   | #direction: right              |

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## A worked example

Classes with compartments and inheritance:

![Nomnoml](https://help.gocapable.com/images/att1418100876.svg)

The source, which you can paste into a new diagram and edit:

```
#direction: down
#spacing: 40

[Payment|
  amount: Money;
  currency: string|
  authorise();
  capture()
]

[Payment] <:- [CardPayment]
[Payment] <:- [BankTransfer]
[CardPayment] +-> [Card|
  last4: string;
  expiry: date
]
[Payment] -> [Ledger]
```

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## A few things that catch people out

* Directives at the top control layout: #direction, #spacing, #fill.
* Pipes separate compartments, semicolons separate the lines inside one.
* For full UML with sequence and activity diagrams, use PlantUML.

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## Related

[VegaFull control when a standard chart is not enough.](https://help.gocapable.com/diagrams/vega.html)

[Vega-LiteA real chart in about ten lines.](https://help.gocapable.com/diagrams/vega-lite.html)

[ExamplesWorking diagrams you can copy.](https://help.gocapable.com/diagrams/examples.html)

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_Learn one properly. Borrow the rest when you need them._