m4 crimes for metaprogramming Processing (eighty-twenty news)

Back in June, I made a quick-and-dirty attempt to get the big-bang model of functional UI running in Processing 4.

Unfortunately Processing uses a dialect of Java predating introduction of Java Records (JEP395), so I, er, creatively broke out m4 as a preprocessor.

The resulting macros turn this:

_record(Rect extends Pict, {{float x, float y, float w, float h}}, {{
  public void render() {
    rectMode(CORNER);
    rect(this.x, this.y, this.w, this.h);
  }
}});

into this:

class Rect extends Pict {
  public final float x;
  public final float y;
  public final float w;
  public final float h;
  public Rect(float x, float y, float w, float h) {
    this.x = x;
    this.y = y;
    this.w = w;
    this.h = h;
  }

  public void render() {
    rectMode(CORNER);
    rect(this.x, this.y, this.w, this.h);
  }
};

The macros

Not yet properly factored out into a utility library or anything, just pasted straight at the top of the file. Shield your eyes!

/* -*- mode: java; c-basic-offset: 2 -*- */
changecom(`//')dnl
changequote(`{{',`}}')dnl
dnl);
define({{_record}}, {{class $1 {_record_fields($2,)
  public _record_classname($1)($2) {_record_inits($2,)
  }
$3dnl;
}{{}}}})dnl;
define({{_record_fields}}, {{ifelse({{$#}}, {{1}},, {{
  public final $1;$0(shift($@))}})}})dnl;
define({{_record_inits}}, {{ifelse({{$#}}, {{1}},, {{
    this._record_fieldname({{$1}}) = _record_fieldname({{$1}});$0(shift($@))}})}})dnl;
define({{_record_classname}}, {{regexp({{$1}}, {{^\(\w+\).*$}}, {{\1}})}})dnl;
define({{_record_fieldname}}, {{regexp({{$1}}, {{^.+\s\(\w+\)$}}, {{\1}})}})dnl;
dnl;//---------------------------------------------------------------------------