6.11.12 Synonyms ¶

The defining word synonym allows you to define a word by name that has the same behaviour as some other word. Here are two situation where this can be useful:

• When you want access to a word’s definition from a different word list (for an example of this, see the definitions in the Root word list in the Gforth source).
• When you want to create a synonym; a definition that can be known by either of two names (for example, THEN and ENDIF can be defined as synonyms).

Synonym ( "name" "oldname" –  ) tools-ext “Synonym”

Define name to behave the same way as oldname: Same interpretation semantics, same compilation semantics, same to, +to, is, action-of and addr semantics.

Gforth also offers the Gforth-specific alias, that allows to define another word with the same execution token, but otherwise default semantics (no copying of compilation or other semantics). You can then change, e.g., the compilation semantics with, e.g., immediate.

Alias ( xt "name" –  ) gforth-0.2 “Alias”

Define name as a word that performs xt. Unlike for deferred words, aliases don’t have an indirection overhead when compiled.

Example:

: foo ." foo" ; immediate

' foo Alias bar1           \ bar1 is not an immediate word
' foo Alias bar2 immediate \ bar2 is an immediate word
synonym bar3 foo           \ bar3 is an immediate word
: test-bar1 bar1 ; \ no output
test-bar1          \ "foo"
: test-bar2 bar2 ; \ "foo"
test-bar2          \ no output
: test-bar3 bar3 ; \ "foo"
test-bar3          \ no output

Both synonyms and aliases have a different nt than the original, but ticking it (or using name>interpret) produces the same xt as the original (see Tokens for Words).