Info Catalog elisp: Functions elisp: Top elisp: Customization

elisp: Macros

 
 13 Macros
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 “Macros” enable you to define new control constructs and other language
 features.  A macro is defined much like a function, but instead of
 telling how to compute a value, it tells how to compute another Lisp
 expression which will in turn compute the value.  We call this
 expression the “expansion” of the macro.
 
    Macros can do this because they operate on the unevaluated
 expressions for the arguments, not on the argument values as functions
 do.  They can therefore construct an expansion containing these argument
 expressions or parts of them.
 
    If you are using a macro to do something an ordinary function could
 do, just for the sake of speed, consider using an inline function
 instead.  Inline Functions.
 

Menu

 
· Simple Macro            A basic example.
· Expansion               How, when and why macros are expanded.
· Compiling Macros        How macros are expanded by the compiler.
· Defining Macros         How to write a macro definition.
· Problems with Macros    Don’t evaluate the macro arguments too many times.
                               Don’t hide the user’s variables.
· Indenting Macros        Specifying how to indent macro calls.
 

Info Catalog elisp: Functions elisp: Top elisp: Customization