On 2018-04-29 07:57, Tim Peters wrote:
[Tim Delaney <timothy.c.dela...@gmail.com>]
My big concern here involves the:
if local(m = re.match(regexp, line)):
print(m.group(0))
example. The entire block needs to be implicitly local for that to work
-
what happens if I assign a new name in that block?
[Tim Peters]
I really don't know what you're asking there. Can you make it
concrete? If, e.g., you're asking what happens if this appeared after
the `print`:
x = 3.14
then the answer is "the same as what would happen if `local` had not
been used". We can't know what that is without context, though.
Maybe x is global. Maybe x was declared nonlocal earlier. Maybe it's
function-local. ...
[Tim D]
That's exactly what I was asking, and as I understand what you're saying, we
would have a local name m available in the indented block which went away
when the block ended, but any names modified in the block are not local to
the block. That seems likely to be a source of errors.
If you what you _want_ is a genuinely new scope, yes. But no actual
use cases so far wanted that at all.
This is the kind of code about which there have been background
complaints "forever":
m1 = regexp1.match(line)
m2 = regexp2.match(iine)
if m1 and m2:
do all sorts of stuff with m1 and/or m2,
including perhaps modifying local variables
and/or global variables
and/or nonlocal variables
The complaints are of two distinct kinds:
1. "I want to compute m1 and m2 _in_ the `if` test".
2. "I don't want these temp names (m1 and m2) accidentally
conflicting with local names already in scope - if these names
already exist, I want the temp names to shadow their
current bindings until the `if` structure is done".
So,
if local(m1=regexp1.match(line),
m2 = regexp2.match(iine),
m1 and m2):
intends to address both complaints via means embarrassingly obvious to
the most casual observer ;-)
How about these:
local m1, m2:
m1 = regexp1.match(line)
m2 = regexp2.match(line):
if m1 and m2:
...
local m1, m2:
if (m1 := regexp1.match(line)) and (m2 := regexp2.match(line)):
...
local m1=regexp1.match(line), m2=regexp2.match(line):
if m1 and m2:
...
?
[snip]
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