Hi Bruno,
On 3/29/24 4:16 AM, Bruno Haible wrote:
>> I was not a fan of adding another value to the left side of this
>> assignment:
>>
>> emit, uses_subdirs = self.emitter.lib_Makefile_am(basename, ...)
>
> Why not? This is perfectly normal functional programming style.
> Lisp has it ("multiple values"), ISO C has it ("struct" as return value),
> Python has it ("tuplie"), ...
Probably mostly habit/personal preference now that I think about it. I
can only read very simple Lisp code, sadly. I would caveat the C
struct comparison a bit. One might go another direction with
incomplete types, function pointers, etc. Though I'd imagine they
would prefer C++ in that case. :)
I likely got annoyed by some terrible code I wrote a long time ago.
You have to be a bit careful with unpacking tuples:
(a, b) = (1, 2, 3)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: too many values to unpack (expected 2)
(a, b, _) = (1, 2, 3)
print(f'{a} {b}')
1 2
That wouldn't be a problem in that case, but something to be careful
about.
> For example, here: If current_edit is 1, and we remove the element
> at index 1:
>
>>>> l = ['a','b','c']
>>>> l.pop(1)
> 'b'
>>>> l
> ['a', 'c']
>
> we need to continue at index 1, not index 2. Otherwise we miss the 'c'.
Oops, yes you are right. Thanks.
> Also, the
> if dictionary['var']:
> lines that were meant to detect already-handled entries can now be dropped.
>
> But I kept wondering why the original code is not working. The reason is that
> each makefiletable[index] access creates a clone of the dict object, and thus
> dictionary.pop('var')
> has an effect on the dictionary variable but not on the makefiletable.
Interesting. I thought it was just pointless, so I didn't bother
changing it. Sort of like a pointless C cast or something...
I have been wanting to change empty list initialization from 'list()'
to '[]' since we have both at the moment. Also some lines like this
confuse the LSP I use:
old_table += [tuple([dest, src])]
# and
result = tuple([filetable, transformers])
It can't tell if those lines are a tuple or a list...
Maybe that would be a good opportunity to find more bugs like that.
> Once I fix this, I get a KeyError from
> if dictionary['var']:
> indicating that this code never worked.
Yes, that code has been around for a long time. I didn't change it
because I didn't notice any errors from it.
Your method would be correct. You could also write something like:
if dictionary.get('var', 'default-value'):
which might make sense in other situations. Thanks for fixing that.
Collin
