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Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 32 |
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@@ -1,3 +1,35 @@ +2014-02-23 Kaz Kylheku <kaz@kylheku.com> + + Introducing some changes for improved handling of special variables. + Saving and restoring of individual variables is very silly + and it's making it difficult to implement function parameters + that are rebindings of special variables. + + Let's have a global pointer to a dynamic environment called dyn_env. + Let's make it part of the extended_jmp_buf structure, so that it's + implicitly saved and restored across exception handling. + + Special variable lookups go through the dyn_env chain, and fall back on + the global bindings. + + To override some specials, we just push a new dynamic environment and + stick them there. (As a bonus, the bindings can even be repeated in the + lexical environment (i.e. the same objects), so they can be found + faster. We have to make sure we remove that environment when we + leave the scope in the normal way. If we unwind out, it is done + automatically by extended_longjmp mechanism. + + * eval.c (dyn_env): New global variable. + (lookup_var, lookup_var_l): If env is nil, look in the dyn_env + first, and only if that fails, look in the global bindings top_vb. + + * signal.h (extended_jmp_buf): New member, de, for saving/restoring + dyn_env. This structure is now used whether or not we have signals. + (extended_setjmp, extended_longjmp): Updated to save and restore + dyn_env, and to do it regardless of whether there is POSIX signal + support. + (dyn_env): Declared here. + 2014-02-22 Kaz Kylheku <kaz@kylheku.com> * eval.c (symbol_function): Retrieve the global macro binding if the |