Next: , Previous: , Up: User-defined Defining Words   [Contents][Index] User-defined defining words with colon definitions

You can create a new defining word by wrapping defining-time code around an existing defining word and putting the sequence in a colon definition.

For example, suppose that you have a word stats that gathers statistics about colon definitions given the xt of the definition, and you want every colon definition in your application to make a call to stats. You can define and use a new version of : like this:

: stats
  ( xt -- ) DUP ." (Gathering statistics for " . ." )"
  ... ;  \ other code

: my: : latestxt postpone literal ['] stats compile, ;

my: foo + - ;

When foo is defined using my: these steps occur:

You can use see to decompile a word that was defined using my: and see how it is different from a normal : definition. For example:

: bar + - ;  \ like foo but using : rather than my:
see bar
: bar
  + - ;
see foo
: foo
  `foo stats + - ;

`foo is another way of writing ['] foo.



Strictly speaking, the mechanism that compile, uses to convert an xt into something in the code area is implementation-dependent. A threaded implementation might spit out the execution token directly whilst another implementation might spit out a native code sequence.

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