From 2990640d8af1d1fd6ba264ced46e741b9dc091d0 Mon Sep 17 00:00:00 2001 From: Jeremy Hylton Date: Mon, 10 Dec 2001 00:53:18 +0000 Subject: [PATCH] Add a comment explaining the st_symbols cache. --- Python/symtable.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/Python/symtable.c b/Python/symtable.c index 33e1a579087..e48eaea1d54 100644 --- a/Python/symtable.c +++ b/Python/symtable.c @@ -4,6 +4,20 @@ #include "graminit.h" #include "structmember.h" +/* The compiler uses this function to load a PySymtableEntry object + for a code block. Each block is loaded twice, once during the + symbol table pass and once during the code gen pass. Entries + created during the first pass are cached for the second pass, using + the st_symbols dictionary. + + The cache is keyed by st_nscopes. Each code block node in a + module's parse tree can be assigned a unique id based on the order + in which the nodes are visited by the compiler. This strategy + works so long as the symbol table and codegen passes visit the same + nodes in the same order. +*/ + + PyObject * PySymtableEntry_New(struct symtable *st, char *name, int type, int lineno) { @@ -14,7 +28,7 @@ PySymtableEntry_New(struct symtable *st, char *name, int type, int lineno) if (k == NULL) goto fail; v = PyDict_GetItem(st->st_symbols, k); - if (v) /* XXX could check that name, type, lineno match */ { + if (v) { Py_DECREF(k); Py_INCREF(v); return v;