Metadata-Version: 2.1
Name: napkin
Version: 0.5.2
Summary: Python DSL for writing PlantUML sequence diagram
Home-page: https://github.com/pinetr2e/napkin
Author: Hans Jang
Author-email: hsjang8848@gmail.com
License: UNKNOWN
Description: # Napkin 
        
        Napkin is a tool to "write" sequence diagrams effectively as Python code.
        
        
        ## Motivation
        The sequence diagrams are useful tool to capture the behavioural aspect of the
        design. [PlantUML](http://plantuml.com) is a great tool to draw nice sequence
        diagrams with simple human readable plain text.
        
        However, the syntax of PlantUML is hard to use when there are nested calls,
        where lifeline with multiple activation/deactivations are involved.
        Unfortunately, this situation is quite common in sequence diagram for S/W.
        
        For example, consider the following common sequence diagram,
        which is from [Figure 4.2, UML Distilled 3E](https://my.safaribooksonline.com/book/software-engineering-and-development/uml/0321193687/sequence-diagrams/ch04):
        ![Figure 4.2, UML Distilled 3E](images/distributed_control.png)
        
        The PlainUML script for the diagram will be as follows:
        ```plantuml
        @startuml
        participant User
        participant Order
        participant OrderLine
        participant Product
        participant Customer
        
        User -> Order : calculatePrice()
        activate Order
        Order -> OrderLine : calculatePrice()
        activate OrderLine
        OrderLine -> Product : getPrice(quantity:number)
        OrderLine -> Customer : getDiscountedValue(Order)
        activate Customer
        Customer -> Order : getBaseValue()
        activate Order
        Customer <-- Order: value
        deactivate Order
        OrderLine <-- Customer: discountedValue
        deactivate Customer
        deactivate OrderLine
        deactivate Order
        @enduml
        ```
        It is quite hard to follow especially as there are multiple level of nested actviation/deactivation.
        
        What if we express the same thing as the following Python code ?
        ```python
        
        @napkin.seq_diagram()
        def distributed_control(c):
            user = c.object('User')
            order = c.object('Order')
            orderLine = c.object('OrderLine')
            product = c.object('Product')
            customer = c.object('Customer')
        
            with user:
                with order.calculatePrice():
                    with orderLine.calculatePrice():
                        product.getPrice('quantity:number')
                        with customer.getDiscountedValue(order):
                            order.getBaseValue().ret('value')
                            c.ret('discountedValue')
        ```
        `distributed_control` is normal function accepting a context object, `c` to access APIs.
        The function defines objects and the control starts with `user` object, which then calls `orderLine.calculatePrice()`.
        Basically, the sequence diagram is expressed as "almost" normal python code.
        
        There are several advantages in using Python instead of using other special
        syntax language:
        * Easy to write/maintain scripts for the correct diagrams
        * Many common mistakes are detected as normal Python error. For example, method
          call to an undefined object will be just normal Python error.(This can be even
          checked by IDE without running scripts).
        * Any Python editor can become sequence diagram editor
        * There can be many interesting usages by taking advantage of Python as general
          language. For example, we can build a library for patterns.
        
        
        ## Installation
        
        Install and update using `pip`
        ```
        pip install -U napkin
        ```
        
        ## Hello world
        
        Write a simple script called `hello.py` as follows:
        
        ```python
        import napkin
        
        @napkin.seq_diagram()
        def hello_world(c):
            user = c.object('user')
            world = c.object('world')
            with user:
                world.hello()
        ```
        Then, the following command will generate `hello_world.uml`:
        ```
        $ napkin hello.py
        ```
        
        ## More examples
        [See example](./demo/readme_examples.py)
        
Platform: UNKNOWN
Classifier: Development Status :: 3 - Alpha
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Classifier: Intended Audience :: Developers
Classifier: Environment :: Console
Classifier: Topic :: Software Development
Description-Content-Type: text/markdown
