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Adds __rmul__ to collections.deque #2844

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Merged
merged 4 commits into from
Aug 11, 2021
Merged

Adds __rmul__ to collections.deque #2844

merged 4 commits into from
Aug 11, 2021

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sobolevn
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Closes #2834

Note: at the moment almost all collections are missing MemoryError corner case, like here: https://github.com/python/cpython/blob/d1ae57027fc39ff60dcfc1b63881400e5ca3ce56/Modules/_collectionsmodule.c#L709-L711

I guess that this is out of scope of this task, related:

I think that some tests in test_deque might hang because of that.

@sobolevn
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Local test produces a very strange result:

» target/debug/rustpython 
Welcome to the magnificent Rust Python 0.1.2 interpreter 😱 🖖
>>>>> from collections import deque
>>>>> d = deque('abc', maxlen=5)
>>>>> d * 1 == deque('abc')
thread 'main' panicked at 'attempt to subtract with overflow', vm/src/stdlib/collections.rs:310:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

@youknowone
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d.len() is 3, maxlen is 5. so 3-5 is overflowed.

@DimitrisJim
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I think that some tests in test_deque might hang because of that.

That's deadlocking, unfortunately. I've idly been trying to find a good way to tackle it. It is for another time, though.

youknowone
youknowone reviewed Aug 11, 2021
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vm/src/stdlib/collections.rs Outdated
let mul_len = mul.len();
let skipped = match self.maxlen.load() {
Some(maxlen) if mul_len > maxlen => mul_len - maxlen,
_ => 0,
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@youknowone youknowone Aug 11, 2021 •
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self.maxlen.load().and_then(|maxlen| mul_len.checked_sub(max_len)).unwrap_or(0)

edited wrapping_sub -> checked_sub

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Thanks!

@DimitrisJim DimitrisJim merged commit 0906728 into RustPython:master Aug 11, 2021
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@DimitrisJim DimitrisJim DimitrisJim approved these changes

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collections.deque does not have __rmul__ method
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@sobolevn @youknowone @DimitrisJim