== <choice> ==

A choice object represents a set of mutually exclusive options:

[[rpimage(zoo_choice.gif)]]
{{{
  <choice id="stats">
    <about>
      <label>Carrier Statistics</label>
      <description>Determines the model for carrier statistics used in bandgap narrowing calculations.</description>
    </about>

    <option>
      <about>
        <label>Boltzmann</label>
        <description>From the Boltzmann transport equation</description>
      </about>
      <value>bte</value>
    </option>

    <option>
      <about>
        <label>Fermi</label>
        <description>Fermi-Dirac statistics</description>
      </about>
    </option>

    <option>
      <about>
        <label>2D Gas</label>
        <description>Includes confinement at material interface</description>
      </about>
      <value>2deg</value>
    </option>
    <default>Boltzmann</default>
  </choice>
}}}
Each {{{<option>}}} has an {{{<about>}}} section with a label and an optional description.  The label represents the option in the combobox, and the description appears in a tooltip that pops up when the option is currently selected.

Each {{{<option>}}} can also have a {{{<value>}}} used to represent it.  The {{{<value>}}} for the selected option is passed along as the current value for the choice in the driver file passed to the underlying simulator.  If there is no value, then the {{{<label>}}} is used instead.  Either the {{{<label>}}} or the {{{<value>}}} can be used in the {{{<default>}}} specification to set the default choice.

You can see working code in the [browser:trunk/examples/zoo zoo of examples] in the [browser:trunk/examples/zoo/choice choice example] or on the hub in the directory /apps/rappture/examples/zoo/choice.