FunctionDefinition

All Known Implementing Classes:

BuiltInFunctionSet.Entry, MemoFunction, StreamableUserFunction, UserFunction, XQueryFunction
```
public interface FunctionDefinition
```
A FunctionDefinition represents the declaration of a user-defined function in XQuery or XSLT; in 4.0 a function definition has an arity range. The minimum arity is the number of mandatory parameters, the maximum arity is the number of optional plus mandatory parameters; optional parameters have a default value which is supplied as an expression.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Expression`	`getDefaultValueExpression(int i)`	Get the default value expression of the Nth parameter, if any
`StructuredQName`	`getFunctionName()`	Get the name of the function
`int`	`getMinimumArity()`	Get the number of mandatory arguments (the lower bound of the arity range)
`int`	`getNumberOfParameters()`	Get the number of declared parameters (the upper bound of the arity range)
`StructuredQName`	`getParameterName(int i)`	Get the name (keyword) of the Nth parameter
`int`	`getPositionOfParameter(StructuredQName name)`	Get the position in the parameter list of a given parameter name

- Method Detail
  - getFunctionName
```
StructuredQName getFunctionName()
```
    Get the name of the function
    
    Returns:
    
    the function name
  - getNumberOfParameters
```
int getNumberOfParameters()
```
    Get the number of declared parameters (the upper bound of the arity range)
    
    Returns:
    
    the number of declared parameters
  - getMinimumArity
```
int getMinimumArity()
```
    Get the number of mandatory arguments (the lower bound of the arity range)
    
    Returns:
    
    the number of mandatory arguments
  - getParameterName
```
StructuredQName getParameterName(int i)
```
    Get the name (keyword) of the Nth parameter
    
    Parameters:
    
    i - the position of the required parameter
    
    Returns:
    
    the expression for computing the value of the Nth parameter
  - getDefaultValueExpression
```
Expression getDefaultValueExpression(int i)
```
    Get the default value expression of the Nth parameter, if any
    
    Parameters:
    
    i - the position of the required parameter
    
    Returns:
    
    the expression for computing the value of the Nth parameter, or null if there is none
  - getPositionOfParameter
```
int getPositionOfParameter(StructuredQName name)
```
    Get the position in the parameter list of a given parameter name
    
    Parameters:
    
    name - the name of the required parameter
    
    Returns:
    
    the position of the parameter in the parameter list, or -1 if absent