<virtualType name="Magento\MediaContent\Model\Content\Config\Reader"
             type="Magento\Framework\Config\Reader\Filesystem">
    <arguments>
        <argument name="fileName" xsi:type="string">
            media_content.xml
        </argument>
        <argument name="converter" xsi:type="object">
            Magento\MediaContent\Model\Content\Config\Converter
        </argument>
        <argument name="schemaLocator" xsi:type="object">
            Magento\MediaContent\Model\Content\Config\SchemaLocator
        </argument>
        <argument name="idAttributes" xsi:type="array">
            <item name="/config/search/patterns/pattern"
                  xsi:type="string">
                name
            </item>
        </argument>
    </arguments>
</virtualType>

This is a virtual type configuration.

This configuration is for the base area. Base area configurations will apply to all the sub-applications.

This virtualType configuration tells the Object Manager when a user wants a virtual Magento\MediaContent\Model\Content\Config\Reader object that it should return a Magento\Framework\Config\Reader\Filesystem object.

This configuration tells the Object Manager that when a user wants a Magento\MediaContent\Model\Content\Config\Reader object that the following arguments should be used in the foo object's constructor.

• $fileName = "media_content.xml";
• $converter = new Magento\MediaContent\Model\Content\Config\Converter (...)
• $schemaLocator = new Magento\MediaContent\Model\Content\Config\SchemaLocator (...)
• $idAttributes = [...items...];

<virtualType name="Magento\MediaContent\Model\Content\Config\Data"
             type="Magento\Framework\Config\Data">
    <arguments>
        <argument name="reader" xsi:type="object">
            Magento\MediaContent\Model\Content\Config\Reader
        </argument>
        <argument name="cacheId" xsi:type="string">
            Media_Content_Patterns_CacheId
        </argument>
    </arguments>
</virtualType>

This is a virtual type configuration.

This configuration is for the base area. Base area configurations will apply to all the sub-applications.

This virtualType configuration tells the Object Manager when a user wants a virtual Magento\MediaContent\Model\Content\Config\Data object that it should return a Magento\Framework\Config\Data object.

This configuration tells the Object Manager that when a user wants a Magento\MediaContent\Model\Content\Config\Data object that the following arguments should be used in the foo object's constructor.

• $reader = new Magento\MediaContent\Model\Content\Config\Reader (...)
• $cacheId = "Media_Content_Patterns_CacheId";