Enriches (return) values transparently with extra data.
Python, 33 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | # Enriches (return) values transparently with extra data.
def RICHVALUE(v, **kwargs):
try:
class _RICHVALUE(type(v)):
pass
vv=_RICHVALUE(v)
except TypeError:
import copy
vv=copy.copy(v)
vv.__dict__.update(kwargs)
return vv
def f():
return RICHVALUE(7, extra="hello")
def g():
class X: pass
return RICHVALUE(X(), extra="hello")
def h(want_extra=False):
class Y(object): pass
y=Y()
if want_extra:
return RICHVALUE(y, extra="hello")
return y
ret=f()
print ret, ret+1, ret.extra
ret=g()
print ret, ret.extra
ret=h(want_extra=True)
print ret, getattr(ret,'extra',"???")
|
While evolving code, there is often a need to enrich an existing simple return scheme of a function by extra/optional return values. Using (variable lenght) return tuples often introduces puzzles - and the pychecker yells. In such cases the RICHVALUE recipe offers a transparent method for adding extra return values.
Drawbacks: Pickling exceptions, if such enriched values (builtin types) are pickled without typecasting.
Tags: shortcuts
