Whats the difference between Command Parameters and Menu Contribution Parameters

I can see that parameters can be defined for Comma开发者_开发知识库nds defined using the Commands extension point. I can not define a value for these command parameters.

I can also define parameters under the Command element in the menus extension point when defining menu contributions. I can define a value for the parameter here.

Are the command parameters in Command different from parameters in menu contributions? If they are different how are they different?

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The plugin org.eclipse.ui.command, Let you declare parameters for your commands. When you add parameter to your command, you have to set and id, type and a list of possible values for your parameter implementing IParameterValues.

After that, you can add this command to a menu item with parameters and its values.

For example, Imagine you have a command with id org.rcp.commands.new. And It's defined a parameter with name "type" and posible values (file, project and folder). You'll be able to add three menu item with commandId = "org.rcp.commands.new" for each parameter

Sample of plugin.xml

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Find more info in this link: http://blog.eclipse-tips.com/2008/12/commands-part-3-parameters-for-commands.html

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The difference is basically the same as the declaration of a function argument - func(int a) and the specification of a named argument in a function call - e.g. func(a=1).

Here is a small example that illustrates the difference between the two. The following declaration specifies a new command with with a single parameter. The parameter has both an id and a name. The id is used later, whereas the name is only used in a few views and can be disregarded here. So this is really just showName(String header).

<extension
    point="org.eclipse.ui.commands">
<command
    categoryId="com.rcpcompany.training.demo33.providers.ui.category.demoCommands"
    description="Shows the name of the current resource"
    id="com.rcpcompany.training.demo33.providers.ui.commands.showName"
    name="&amp;Show Name">
    <commandParameter
        id="header"
        name=”Header“ />
</command>
</extension>

Here we have a use of the same command with a value for the header argument. So this is showName(header="The selected resource is....").

<menuContribution locationURI="toolbar:org.eclipse.ui.main.toolbar">
<toolbar id="com.rcpcompany.training.demo33.providers.ui.toolbar1">
    <command
        commandId="com.rcpcompany.training.demo33.providers.ui.commands.showName">
    <parameter
        name="header"
        value="The selected resource is...." />
    </command>
</toolbar>
</menuContribution>

Note that it is the id attribute of the parameter declaration that is the name attribute of the parameter use... So it is header and not Header.