#MACRO...#ENDMACRO


Preprocessor directive to define a multiline macro

Syntax:
#macro identifier [?] ( [ parameters ] )
body
#endmacro

#macro identifier [?] ( [ parameters, ] variadic_parameter... )
body
#endmacro

Description:
#macro is the multi-line version of #define.

If using the optional question mark (?) after the identifier in the definition syntax, macros with parameters can be invoked without using parentheses around the arguments.
Note: Beware of the possibility of triggering so a conflict with expressions containing the name of the macro as one of their terms.

Note: Unlike the function-like #define declaration, spaces can be put between the macro name and the opening parenthesis for any declaration syntax of macro.

WARNING: In the macro body, it may be mandatory to have to surround by parentheses any used parameter if it is inside an expression with one operator at least, in order to not undergo an unwanted precedence change of operators (if passing as argument an expression with also operators).

Examples:
' macro as an expression value

#macro Print1( a, b )
    a + b
#endmacro

Print Print1( "Hello ", "World!" )

/' Output :
Hello World!
'/

' macro as multiple statements

#macro Print2( a, b )
    Print a;
    Print " ";
    Print b;
    Print "!"
#endmacro

Print2( "Hello", "World" )

/' Output :
Hello World!
'/

' macro with a variadic parameter

#macro test1( arg1, arg2... )
    Print arg1
    #if #arg2 = ""
        Print "2nd argument not passed"
    #else
        Print arg2
    #endif
#endmacro

test1( "1", "2" )
Print "-----------------------"
test1( "3" )
Print "-----------------------"
test1( 5, 6 )
Print "-----------------------"
test1( 7 )

/' Output :
1
2
-----------------------
3
2nd argument Not passed
-----------------------
 5
 6
-----------------------
 7
2nd argument Not passed
'/

' macro with a variadic parameter which can contain several sub-parameters:
'   To distinguish between the different arguments passed by variadic_parameter,
'   you can first convert variadic_parameter to a string using the Operator # (Preprocessor Stringize),
'   then differentiate in this string (#variadic_parameter) each passed argument by locating the separators (usually a comma).

#macro test2( arg1, arg2... )
    Print "'" & Trim(#arg1) & "'"
    Scope
        Dim As String s = Trim(#arg2)
        If s <> "" Then
            Do
                Dim As Integer k = InStr(1, s, ",")
                If k = 0 Then
                    Print "'" & s & "'"
                    Exit Do
                End If
                Print "'" & Left(s, k - 1) & "'"
                s = Trim(Mid(s, k+1))
            Loop
        End If
    End Scope
#endmacro

test2( 5 )
Print "----"
test2( 5,6, 7, , 9, 10, ,,13, 14 )

/' Output :
'5'
----
'5'
'6'
'7'
''
'9'
'10'
''
''
'13'
'14'
'/

Differences from QB:
See also:
Back to Preprocessor
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