Nesting definitions.

[SirWumpus]

I've had a GitHub issued opened concerning Post4. At the heart of it is the issue of nesting definitions. This code from Rosetta:

: compose ( xt1 xt2 -- xt3 )
  >r >r :noname
     r> compile,
     r> compile,
     postpone ;
;

I contend this is invalid according to the Forth 200x draft 19.1:

3.4.5 Compilation

A program shall not attempt to nest compilation of definitions.

During the compilation of the current definition, a program shall not execute any defining word, :NONAME, or any definition that allocates dictionary data space. The compilation of the current definition may be suspended using [ (left-bracket) and resumed using ] (right-bracket). While the compilation of the current definition is suspended, a program shall not execute any defining word, :NONAME, or any definition that allocates dictionary data space.

• Am I misinterpreting the 200x draft?
• Was this valid against the older 1994 standard?

[ruv]

This definition for compose does not contain nested definitions, and there is no attempt to nest compilation of definitions. So, this definition for compose is standard-compliant in Forth-1994, as well as in Forth-2012.

A problem can occur when executing compose. Namely, if it is executed while another definition is being compiled (i.e., the current definition is present), it violates 3.4.5.

A correct usage example:

' foo ' bar compose constant func-foobar

In this case, the current definition is absent when compose is executed.

An incorrect usage example:

: baz  [ ' foo  ' bar compose compile, ] ;

In this case, the current definition is present when compose is executed — namely, compilation for baz has been started and is not yet finished.

[SirWumpus]

@ruv Thank you for quick response and clarity.