Provisional fix for writefile() [SF bug # 541730].
The problem was that an exception can occur in the text.get() call or
in the write() call, when the text buffer contains non-ASCII
characters. This causes the previous contents of the file to be lost.
The provisional fix is to call str(self.text.get(...)) *before*
opening the file, so that if the exception occurs, we never open the
file.
Two orthogonal better solutions have to wait for policy decisions:
1. We could try to encode the data as Latin-1 or as UTF-8; but that
would require IDLE to grow a notion of file encoding which requires
more thought.
2. We could make backups before overwriting a file. This requires
more thought because it needs to be fast and cross-platform and
configurable.
Original patches were:
python/dist/src/Tools/idle/IOBinding.py:1.6
Add is_constant_false(), rev 1.41.
Fixed print handling, rev. 1.41.
Handle private names, 1.42.
Make sure JUMP_ABS and POP_BLOCK blocks are contiguous, rev. 1.44.
Make sure class object has no co_varnames, rev. 1.45.
Fix typo in visitDict(), rev. 1.46.
Generate correct code for continue in try/except, rev. 1.47.
Fix for sibling nodes that define the same free variable, rev. 1.6.
Handle private names, rev. 1.7.
Fix bug in handling of statements like "l[x:y] = 2", reb. 1.8.
Fix symbol problem with slice assignment, rev. 1.9.
SF bug 430991: wrong co_lnotab
Armin Rigo pointed out that the way the line-# table got built didn't work
for lines generating more than 255 bytes of bytecode. Fixed as he
suggested, plus corresponding changes to pyassem.py, plus added some long
overdue docs about this subtle table to compile.c.
Always emit a SET_LINENO 0 at the beginning of the module. The
builtin compiler does this, and it's much easier to compare bytecode
generated by the two compilers if they both do.
Move the SET_LINENO inside the FOR_LOOP block for list
comprehensions. Also for compat. with builtin compiler.
Fix annoying bugs in flow graph layout code. In some cases the
implicit control transfers weren't honored. In other cases,
JUMP_FORWARD instructions jumped backwards.
Remove unused arg from nextBlock().
pycodegen.py
Add optional force kwarg to set_lineno() that will emit a
SET_LINENO even if it is the same as the previous lineno.
Use explicit LOAD_FAST and STORE_FAST to access list comp implicit
variables. (The symbol table doesn't know about them.)
