When structuring a heterogeneous tuple, if the input has too few or many elements, this PR now raises an error. The error is a ValueError in non-detailed validation.

Two existing tuple-structuring tests had to be fixed (in the zero-element case).

Fixes #57

Hello, thanks for contributing.

Unfortunately this PR makes the happy path almost twice slower.

$ pyperf timeit -g -s 'from cattrs import structure; t = tuple[int, str];v = [1, 2]' 'structure(v, t)'
old: Mean +- std dev: 1.50 us +- 0.04 us
new: Mean +- std dev: 2.94 us +- 0.14 us

# Detailed validation false:
old: Mean +- std dev: 1.39 us +- 0.06 us
new: Mean +- std dev: 1.95 us +- 0.09 us

You're overcomplicating it with the _zip_strict thing. One length comparison after the transformation should be enough, right?

One length comparison after the transformation should be enough, right?

The one case that that doesn't solve is when obj is a un-sized iterable with more values than the tuple type. If you're fine with that trade-off, then I'll make the change

What is an un-sized operable with Moreno values?

What is an un-sized operable with Moreno values?

Ah, autocorrect. I've updated my previous message

Doing the post-check comparing the result length with the input (latest commit) gives benchmark results:

• Detailed validation:
  • Before: 1.96 ± 0.14 μs
  • After: 2.10 ± 0.15 μs
• Not-detailed validation:
  • Before: 1.83 ± 0.09 μs
  • After: 1.98 ± 0.16 μs

Codecov Report

Merging #283 (75fdc3d) into main (b1a681a) will increase coverage by 0.04%. The diff coverage is 100.00%.

:exclamation: Current head 75fdc3d differs from pull request most recent head 8354a76. Consider uploading reports for the commit 8354a76 to get more accurate results

@@            Coverage Diff             @@
##             main     #283      +/-   ##
==========================================
+ Coverage   97.01%   97.05%   +0.04%     
==========================================
  Files          16       16              
  Lines        1339     1358      +19     
==========================================
+ Hits         1299     1318      +19     
  Misses         40       40              

Impacted Files	Coverage Δ
src/cattrs/converters.py	98.26% <100.00%> (+0.08%)	:arrow_up:

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I'll merge this in now. I might work on it a little more myself. Thanks!