Macros
Erlang macros are written as shown here:
| | -define(Constant, Replacement). |
| | -define(Func(Var1, Var2,.., Var), Replacement). |
Macros are expanded by the Erlang preprocessor epp when
an expression of the form ?MacroName is encountered.
Variables occurring in the macro definition match complete forms in the
corresponding site of the macro call.
| | -define(macro1(X, Y), {a, X, Y}). |
| | |
| | foo(A) -> |
| | ?macro1(A+10, b) |
That expands into this:
| | foo(A) -> |
| | {a,A+10,b}. |
In addition, a number of predefined macros provide information about the current module. They are as follows:
-
?FILEexpands to the current filename. -
?MODULEexpands to the current module name. -
?LINEexpands to the current line number.
Control Flow in Macros
Inside a module, the following ...
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