Debugging Iterables

Use debugIterable() when you want a quick snapshot of what an iterator is currently exposing without writing custom dump code around every experiment.

Basic usage

use function FastForward\Iterator\debugIterable;

$it = new ArrayIterator([1, 2, 3]);
debugIterable($it, 'Section Title');

Expected output:

=== Section Title ===

Length: 3
Output: [
  0 => 1,
  1 => 2,
  2 => 3,
]

When it is especially useful

after composing several iterators and losing track of the final output shape;
while comparing ChainIterableIterator , InterleaveIteratorIterator , and ZipIteratorIterator ;
while checking how grouping iterators structure their arrays;
while verifying whether keys were preserved or normalized.

Tips

Pass a section title so multiple debug blocks are easy to scan in one script.
Debug early in the pipeline and again at the end if you are composing several wrappers.
Remember that debugIterable() calls count() . That is useful, but it also means the underlying iterator should support safe counting.