Function

Class

Class `HtmlContainer`

This widget represents a collection of HTML object tags and defines a set of methods to manipulate the collection and to render the collection, making this class suitable for use as a base class for more complex widgets which are composed of several HTML objects. (ie. It defines a tipical Composition pattern method interface).

Method Summary

add widget ...
Adds one or more widgets into the container.

clear
Empties the container.

constructor [widget ...]
Initializes and adds one or more widgets into the container.

get attribName
Fetches the value of an attribute.

getWidgets
Fetches a list with the widgets it contains.

init attribList
Initializes the values of a set of attributes.

render
Renders the container and its contents by generating the apropriate HTML text.

render-epilogue
Renders a suffix to the collection of objects.

render-prologue
Renders a prefix to the collection of objects.

set attribName attribValue
Changes the values of one of the widget attributes.

Method Detail

add

HtmlContainer add widget ...

Adds one or more widgets into the container.

Parameters:: widget - An object of any type, supposedly a widget, that must respond to a render method. It can also be a string.
Returns:: A reference to the object for which the method was called.

Inserts the widgets received as arguments to the end of the list of widgets managed by this container.

If one of the arguments is a string an HtmlPlainString is automatically created and initialized with that string. The HtmlPlainString is then added to the container.

clear

HtmlContainer clear

Empties the container.

Returns:: A reference to the object for which the method was called.

Removes all the widgets it had received through the add method. The container is thus emptied.

constructor

HtmlContainer constructor [widget ...]

Initializes and adds one or more widgets into the container.

Parameters:: widget - An object of any type, supposedly a widget, that must respond to a render method.

Initializes the container such that it now contains the widgets received as arguments.

get

HtmlContainer get attribName

Fetches the value of an attribute.

Parameters:: attribName - Symbol identifying the attribute whose value is being fetched.
Returns:: The value of the attribName attribute.

The attribName argument must be the same as one of the symbols passed to the init method.

getWidgets

HtmlContainer getWidgets

Fetches a list with the widgets it contains.

Returns:: A list with the widgets it contains.

The list that gets returned contains all the widgets received with the add method, in the same order by which they got added.

init

HtmlContainer init attribList

Initializes the values of a set of attributes.

Parameters:: attribList - A list with the attributes and its values.
Returns:: A reference to the object for which the method was called.

Specifies and initializes the attributes of the widget. These will be the attributes known to the set and get methods.

The attribList argument contains the attributes names and values. It is a list where each element specifies an attribute. Each element is a two element list: a symbol identifying the attribute and its new value.

render

HtmlContainer render

Renders the container and its contents by generating the apropriate HTML text.

Returns:: A reference to the object for which the method was called.

Generates the HTML representation of the HtmlContainer and its contents by eventually calling the render method for each of the widgets it contains. The exact procedure is as follows.

The HtmlContainer starts by invoking the render-prologue method on itself. Then calls render for every widget received with its add method. The calls are performed in the same order the widgets were received. Finally invokes render-epilogue on itself.

The render-prologue and render-epilogue methods are supposed to be redefined in classes derived from HtmlContainer.

render-epilogue

HtmlContainer render-epilogue

Renders a suffix to the collection of objects.

The implementation of this method at HtmlContainer does nothing. The purpose of this method is to allow derived classes to override/extend its definition. (Example: An HtmlForm derived class with define this method to render a </form> HTML tag after rendering all HTML objects contained in the form.)

render-prologue

HtmlContainer render-prologue

Renders a prefix to the collection of objects.

The implementation of this method at HtmlContainer does nothing. The purpose of this method is to allow derived classes to override/extend its definition. (Example: An HtmlForm derived class will define this method to render a <form> HTML tag, before rendering other HTML objects contained within the form.)

set

HtmlContainer set attribName attribValue

Changes the values of one of the widget attributes.

Parameters:: attribName - Symbol identifying the attribute whose value will be modified.; attribValue - The new value of the attribute.
Returns:: A reference to the object for which the method was called.

The attribName argument must be the same as one of the symbols passed to the init method, otherwise a runtime error will occur. Although attribValue can be of any type each attribute expects values of a certain type.

Overview

Module