Functions

[This is preliminary documentation and subject to change.]

NAnt provides a rich set of bulitin functions, that allow you to:

For a full list of supported functions, click here.

Function Call Syntax

To call functions, use prefix::function-name(argument1, ..., argumentN) syntax within expressions. NAnt will (implicitly) try to convert the arguments you pass to functions to correct types and will report an error in case of failure.

For example, assuming you would like to call string::contains('0123456789',1) which expects two string parameters, but you want to pass the second parameter which is an integer. NAnt would attempt to convert the second parameter from int to string, which succeeds and function is called as if it was written as string::contains('0123456789','1').

The following table shows the possible type conversions:

From Type To Type Allowed Remarks
int string Yes The conversion is always possible.
int double Yes The conversion is always possible.
int boolean No Can be done with the if() conditional operator or simply as (value <> 0)
int datetime No You cannot convert from int to datetime.
int timespan No You can use the timespan::from-xxx functions to construct a timespan from a given number of days, months, ....
string int Yes If the string doesn't represent an integer value, an error is reported.
string double Yes If the string doesn't represent a floating point value, an error is reported.
string boolean Yes If the string isn't either true or false (case insensitive), an error is reported.
string datetime Yes If the string doesn't represent a valid date/time, an error is reported. Date/time string format is MM/DD/YYYY HH:MI:SS
string timespan No You can use timespan::parse to construct a timespan from a time indicated by a given string. If the string doesn't represent a valid timespan, an error is reported.
double int Yes If the string doesn't represent an integer value, an error is reported.
double string Yes The converted string uses dot as a fractional part separator so the result looks like 0.1234567
double boolean No You cannot convert from double to boolean.
double datetime No You cannot convert from double to datetime.
double timespan No You can use the timespan::from-xxx functions to construct a timespan from a given number of days, months, ....
boolean int No You cannot convert from boolean to int. You may want to use if(boolvalue,1,0) instead.
boolean string Yes The result is 'True' or 'False' string.
boolean double No You cannot convert from boolean to double.
boolean datetime No You cannot convert from boolean to datetime.
boolean timespan No You cannot convert from boolean to timespan.
datetime int No You cannot convert from datetime to int.
datetime string Yes The result is a datetime string with the following format: MM/DD/YYYY HH:MI:SS
datetime double No You cannot convert from datetime to double.
datetime boolean No You cannot convert from datetime to boolean.
datetime timespan No You can use the value of datetime::get-ticks to construct a timespan using timespan::from-ticks.
timespan int No You cannot convert from timespan to int.
timespan double No You can use timespan::get-ticks to convert from timespan to double.
timespan boolean No You cannot convert from timespan to boolean.
timespan string No You can use timespan::to-string to obtain the string representation of a timespan.
timespan datetime No You cannot convert from timespan to datetime.

Custom Functions

Just as you can extend NAnt with your own tasks it is also possible to implement your own functions for use in build files.

Functions can be implemented in any .NET language and are loaded in the same manner as tasks. ie either by locating your custom function assembly in the NAnt bin directory or using the <loadtasks> task. Example C# code for a Hello World function :

Define a custom function using C#.

                    
[FunctionSet("hello", "Hello")]
public class HelloFunctions : FunctionSetBase {        
    public HelloFunctions(Project project, PropertyDictionary properties) : base(project, properties) {
    }
    [Function("hello-world")]
    public static string HelloWorldfunc() {
        return "Hello World!!";
    }
}
        

and call that function from a build file.

       
<echo message="${hello::hello-world()}" />
        

A quick and easy way to develop new functions is to use the <script> task. This allows you to create and test new functions without the overhead of building an external assembly. The <script> task documentation contains examples of custom function definitions.