Developing Apama Applications > Developing Apama Applications in Event Modeler > Using Functions in Event Modeler > About defining your own functions > About function names
About function names
Functions have several different names:
*The file name — this is the name of the file that contains the function definition, for example, String_String_Concat.fdf.
*The logical name — this is the name specified by the function name attribute in the .fdf file. Event Modeler uses the logical name to distinguish each function from every other function in a particular directory. Within each directory, this value must be unique. For example, SSConcat.
*The display name —this is the name that appears in the Event Modeler Functions tab. For example, Concat. This name also appears in the Rules panel context menu.
The contents of a function definition file contain something like this near the beginning:
<function name="SSConcat" display-string="Concat"
   return-type="string">
In this example, the logical name is SSConcat. The display name is Concat.
For example, it is possible to have the following three functions in the same directory:
Filename:
String_String_Concat.fdf
String_Integer_ Concat.fdf
String_Integer_String_ Concat.fdf
Parameters:
String, String
String, Integer
String, Integer, String
Display name:
Concat
Concat
Concat
Logical name:
ConcatSS
ConcatSI
ConcatSSS
Note that these functions have the same display name but different logical names. An exact duplicate of any of these functions can be in a directory other than the directory that already contains its duplicate.
When you select functions from the rules editor context menu, Event Modeler displays the arguments that each function takes. Consequently, if two functions have the same display name, you can distinguish them by their arguments. For example:
TO_NUMBER(‘choice’ value)
TO_NUMBER (‘text’ value)
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