Dive Into Widgets

This document shows how you can explore the features of the widgets framework from an interactive Python interpreter session. For a structured overview about widgets, reference documentation and more tutorials, please read the Widgets Overview.

The examples below demonstrate some important widgets properties, like template, name, value, params and subclassing. It is suggested that you fire up an interactive session yourself and try to reproduce the examples exactly as given. When you have succeeded with that, try supplying different arguments and values to the widgets constructor or the render method or change the widget template and see how that changes the output of widget.render(). You can use the built-in help function of the interpreter to find out the signature of the different methods.

Next, define your own turbogears.widgets.Widget subclass and add some custom parameters to be passed to the widget template by setting class attributes and adding them to the params class attribute. Again, try what happens if you give different values for those parameters or if you leave them out. Have fun!

Diving in

Now, let’s dive in:

>>> from turbogears.widgets import Widget
>>> class HelloWorldWidget(Widget):
...     template = """
...     <div>Hello World!</div>
...     """
...
>>> hello = HelloWorldWidget()
>>> hello.render()
'<DIV>Hello World!</DIV>'

render() will fail if no templating engine has been loaded yet. To load the default templating engine, excute:

>>> from turbogears.view import load_engines
>>> load_engines()

Back to the widget classes:

>>> class FooBarWidget(Widget):
...     template = """
...     <ul>
...             <li>my name is ${name}</li>
...             <li>my value is ${value}</li>
...     </ul>
...     """
...
>>> foobar = FooBarWidget(name="foobar")
>>> print foobar.render()
'<UL>
                <LI>my name is foobar</LI>
                <LI>my value is </LI>
        </UL>'
>>> print foobar.render(value=5)
'<UL>
                <LI>my name is foobar</LI>
                <LI>my value is 5</LI>
        </UL>'
>>> foobar = FooBarWidget(name="foobar", default=10)
>>> print foobar.render()
'<UL>
                <LI>my name is foobar</LI>
                <LI>my value is 10</LI>
        </UL>'
>>> print foobar.render(value=60)
'<UL>
                <LI>my name is foobar</LI>
                <LI>my value is 60</LI>
        </UL>'
>>> print foobar.render(value=60, name="wrong")
'<UL>
                <LI>my name is foobar</LI>
                <LI>my value is 60</LI>
        </UL>'
>>> class ParamsWidget(Widget):
...     template = """
...     <div>my attitude is ${attitude}</div>
...     """
...     params = ["attitude"]
...     attitude = "high"
...
>>> param = ParamsWidget()
>>> param.render()
'<DIV>my attitude is high</DIV>'
>>> param = ParamsWidget(attitude="medium")
>>> param.render()
'<DIV>my attitude is medium</DIV>'
>>> param.render(attitude="low")
'<DIV>my attitude is low</DIV>'
>>> param.params
['attitude']
>>> param.attitude
'medium'
>>> ParamsWidget.attitude
'high'
>>> class AnotherParamsWidget(ParamsWidget):
...     template = """
...     <div>my attitude is ${attitude} and my favourite language is ${language}</div>
...     """
...     params = ["language"]
...     language = "python"
...
>>> another = AnotherParamsWidget()
>>> another.render()
'<DIV>my attitude is high and my favourite language is python</DIV>'
>>> AnotherParamsWidget.params
['attitude', 'language']
>>> another.params
['attitude', 'language']
>>> AnotherParamsWidget.attitude
'high'
>>> another.attitude
'high'
>>> AnotherParamsWidget.language
'python'
>>> another.language
'python'
>>> another = AnotherParamsWidget(attitude="nice", language="java")
>>> AnotherParamsWidget.attitude
'high'
>>> another.attitude
'nice'
>>> AnotherParamsWidget.language
'python'
>>> another.language
'java'
>>> another.render()
'<DIV>my attitude is nice and my favourite language is java</DIV>'
>>> another.render(attitude="very low", language="ruby")
'<DIV>my attitude is very low and my favourite language is ruby</DIV>'

Dive into ToscaWidgets

All the examples should work with the ToscaWidgets package as well. After you have installed ToscWidgets with

$ easy_install ToscaWidgets

just replace the initial import with

>>> from tw.api import Widget

You don’t need to import turbogears or load a template engine when using ToscaWidgets.