As of the July 25 release of MK 2.3.2 beta, you can now define recursive / self-referential view structures using the subview[^] notation. There's a demo in "examples/selfref.py":
# Demo of the new 2.3 self-referential view structures.
#
# Output:
# 0
# 00000 1
# 11111 1
# 22222 0
# [Property('S', 's'), Property('V', 'sub')]
# 00000 1
# 11111 1
# 22222 0
# [Property('S', 's'), Property('I', 'i'), Property('V', 'sub')]
# ok
import os
try: os.remove("_selfref.mk")
except: pass
import metakit
db = metakit.storage('_selfref.mk',1)
vw = db.getas('data[s:S,sub[^]]')
print len(vw)
v = vw
for i in range(3):
v.append(s=`i`*5)
v = v[0].sub
def show(vw):
for v in [vw[0], vw[0].sub[0], vw[0].sub[0].sub[0]]:
print v.s, len(v.sub)
print vw[0].sub[0].sub[0].sub.structure()
assert len(vw[0].sub[0].sub[0].sub) == 0
try:
metakit.dump(vw[0].sub[0].sub[0].sub[0].sub)
except IndexError:
pass
show(vw)
# note that (recursive!) on-the-fly restructuring works
show(db.getas('data[s:S,i:I,sub[^]]'))
db.commit()
print 'ok'
os.remove("_selfref.mk")September 2001: Use http://e4graph.sourceforge.net to store your nested structures. If someone wanted to do a Python binding that would be really nice..