FUNCTION‑ENDFUNCTION

Define a function

WTSupported in traditional Synergy on Windows
WNSupported in Synergy .NET on Windows
USupported on UNIX
VSupported on OpenVMS
[access] [function_mod ...] FUNCTION name[, return_type[size]][, options, …]
parameter_def
    .
    .
    .
[ENDFUNCTION|END]

Arguments

access

(optional) One of the following access modifiers:

PUBLIC

Access is not restricted. This is the most accessible option.

PROTECTED

Access is limited to the containing class or types derived from the containing class.

PRIVATE

Access is limited to the containing type. This is the least accessible option. (default)

INTERNAL

Access is limited to the current assembly. (Synergy .NET only)

PROTECTED INTERNAL

Access is limited to the current assembly and types derived from the containing class. (Synergy .NET only)

function_mod

(optional) One or more of the following modifiers:

STATIC

Accessed without a reference object. The method can be executed even if the class that contains the method hasn’t been instantiated.

VARARGS

More than the declared number of arguments can be passed to this routine.

name

The name of the function.

return_type

(optional) The return type of the function being defined. See Where data types can be used for the data types that are valid return types. If not specified, the return type defaults to the type of the variable or literal of the first FRETURN statement.

size

(optional) The size of the function return value.

options

(optional) One or more of the following modifiers:

LOCAL | LOCALDATA

Keep record contents constant for as long as the function is activated at one or more levels.

STACK | STACKDATA

Make record contents unique for every activation of the function.

STATIC | STATICDATA

Keep record contents constant throughout every activation of the function.

REENTRANT

Allow multiple active instances of the function.

RESIDENT

Keep the function in memory, even when not in use. (Windows, UNIX only)

ROUND

Use rounding rules for implied‑decimal data types within the function.

TRUNCATE

Use truncation rules for implied‑decimal data types within the function. (traditional Synergy only)

VARARGS

More than the declared number of arguments can be passed to this routine.

parameter_def

Function parameter definitions. See Defining a parameter.

Discussion

The FUNCTION statement identifies the beginning of a user‑defined function.

In traditional Synergy, function names of more than 30 characters are truncated when the routine is linked (although you can specify up to 255 characters as long as the first 30 characters are unique).

The LOCAL, STACK, and STATIC modifiers specify the default state of an unqualified RECORD statement. For example, given the following statement:

function fred ,STACK

all unqualified RECORD statements in function fred are treated as if they are STACK RECORD statements. LOCAL, STACK, and STATIC are mutually exclusive. If you don’t specify one, the default is LOCAL in traditional Synergy (unless the REENTRANT option is specified) and STACK in Synergy .NET. If REENTRANT is specified, unqualified RECORD statements default to STACK data, rather than LOCAL data, for each instance of the function. For example, given the following statement:

function fred ,REENTRANT

all of the unqualified RECORD statements in function fred are treated as if they are STACK RECORD statements.

Note

The REENTRANT modifier causes all local records to be STACK records unless otherwise qualified. Fields in STACK records do not allow default or explicit initial values.

By default, a function cannot be re‑entered. If you specify the REENTRANT option, however, the function can call itself.

Note

Object handles are not allowed in local records in REENTRANT routines.

VARARGS is optional for unprototyped subroutines and functions, but if you want to pass more arguments than declared, it is required when using ‑qnet or strong prototypes (or internal routine prototyping unless ‑qrelaxed:param is set).

On Windows and UNIX, by default, a function may be removed from memory when it is no longer in the calling chain. If you specify the RESIDENT modifier, the function stays in memory.

A program by default rounds all expression results. You can change the default to truncate in traditional Synergy by setting system option #11. However, specifying the ROUND or TRUNCATE option on a FUNCTION statement overrides the default rounding behavior for that function (including if system option #11 is set). You cannot specify both TRUNCATE and ROUND in the same statement. See option #11 for more information about rounding versus truncation rules. (Neither TRUNCATE nor system option #11 are supported in Synergy .NET.)

A function can be declared either inside or outside of a namespace or class. A function declared outside of a class is considered to be a global function. In Synergy .NET, when the compiler generates the .exe or .dll file, it puts any global functions in a new global class called _CL. If a function is also declared outside of a namespace, it is placed in _NS_assemblyname._CL.

See also

Understanding Routines.

Examples

In this example, the implied‑decimal values within avg are processed using truncation rules; therefore, the intermediate result of num1 + num2 (7.5) is truncated to 7. The final result of 7/2 is truncated to 3. However, if we specify ROUND instead of TRUNCATE (or if neither modifier is specified), the implied‑decimal values are processed using rounding rules. Thus, the intermediate result (7.5) is rounded to 8 before being divided by 2, and the final result is 4.

.define TTCHN           ,1
.define MINVAL          ,3
external function                       ;Declare the function and
    avg         ,i                      ; specify an integer result
record
    var1        ,d6.2,          3.4
    var2        ,d6.2,          4.1
proc
    xcall flags(7000000, 1)
    open(TTCHN,i,"tt:")
    if ((var1 = %avg(var1,var2)).GT.MINVAL)
      writes(TTCHN, "Average = " + %string(var1))
endmain
function avg, i, TRUNCATE
    num1        ,d.
    num2        ,d.
record
    rslt        ,i4
proc
    rslt = num1 + num2
    freturn (rslt/2)
endfunction