21.03.18 17:13, Guido van Rossum пише:
Maybe spelunking in the Python 2 branch will help? It seems it was introduced in 2005 by Jeremy Hylton with this comment:
/* The distinction between NEW_BLOCK and NEXT_BLOCK is subtle. (I'd like to find better names.) NEW_BLOCK() creates a new block and sets it as the current block. NEXT_BLOCK() also creates an implicit jump from the current block to the new block. */
That comment (and NEW_BLOCK()) are no longer found in the Python 3 source.
It explains what NEXT_BLOCK() does, but not why it was needed to do this.
NEW_BLOCK() was never used at all.