Re: [RfC] constant PMCs and classes

[Leopold Toetsch]

Brent Dax wrote:

Leopold Toetsch:
# Further we would need for some classes a Const$Class variant, where
the
# set-like vtables throw an exception. These classes should be
# autogenerated from *.pmc for all classes that have a "const_too" or
such
# in their classes $flags.
Isn't The Plan(tm) to use properties for this?
The property 'constant', 'ro' or whatever can only be some kind of 
communication: the HLL is telling the PMC to be read only. We could now 
have in each set-like vtable:

  if (we_have_props && !is_bool(prop("ro")) // pseudo code
     set_the_value ...
  else
     throw_exception
  or we have a different class, that have in the set-like vtable slots 
just the exception. No penalty for rw classes.

The lookup, if we have that property is a hash lookup, the is_bool is 
int, string_bool or a vtable depending on the value of the property.

Setting/resetting the "ro" property could morph() the PMC to the 
const/non-const variant.

I think that "read-only" is import enough (and used internally all over 
the place) to get special treatment.

leo