[OASIS Issue Tracker] Updated: (ODATA-239) Allowing expressions to be passed as parameters to (super) functions

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     [ http://tools.oasis-open.org/issues/browse/ODATA-239?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Michael Pizzo updated ODATA-239:
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I don't think this works; this says that I can pass any arbitrary expression, but doesn't say how that expression is interpreted. Does this mean I can pass any expression to any function, or do we need to have a way to define that a function takes an expression?

How would we differentiate between passing the value of the expression (as we do with firstMemberExpression today) and passing the expression itself?  For example, how do I differentiate between passing the value for revenue versus the expression revenue?

> Allowing expressions to be passed as parameters to (super) functions
> --------------------------------------------------------------------
>
>                 Key: ODATA-239
>                 URL: http://tools.oasis-open.org/issues/browse/ODATA-239
>             Project: OASIS Open Data Protocol (OData) TC
>          Issue Type: New Feature
>          Components: OData CSDL
>    Affects Versions: V4.0_WD01
>         Environment: [Proposed]
>            Reporter: Hubert Heijkers
>
> To be able to use/extend the set of functions that can be used in a $apply query option functions need parameters of type expression, which expression can then be applied to each and every instance in the set they are processing. 
> An very simple example of such a function would:
> $apply=GroupBy()/TopN(N=5, Value=Revenue)
> Where 5 is just a number indicating the top N we are interested in but were 'Revenue' is actually an expression referring to the Revenue property of the entity in the set the function is acting upon. A better example in which this becomes more apparent would be:
> $apply=GroupBy()/TopN(N=5, Value=Revenue sub Cost)
> For build in functions we can obviously simply define this but currently there is no way of defining a 'custom' function that could implement the same behavior because we can't pass in expressions.
> We then could annotate these functions to signal to tools that they can be used in $apply.

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