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35 lines
1.1 KiB
Markdown
35 lines
1.1 KiB
Markdown
# Access Most Recent Return Value In REPL
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One of my favorite features of Ruby's `irb` and `pry` are that you can use `_`
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to reference the most recent return value. Often as we use an interpreter or
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REPL, we end up with _intermediate_ values. That is, we've execute some kind of
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statement which returned a value and we now want to use that resulting value in
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our next statement. Python also supports `_`.
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Let's say I've run a statement that took a while to process, but I forgot to
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assign it to a variable. Instead of re-running the whole thing, I can create a
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variable that references the previous return value using `_`.
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```python
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>>> BytePairEncoding.train_bpe(long_text)
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{'merge_rules': [...], 'vocab': {...}}
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>>> result = _
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>>> list(result.keys())
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['merge_rules', 'vocab']
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```
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Even if I don't necessarily want to assign it a variable, it can be nice to
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reference the previous value as I continue with what I'm doing:
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```python
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>>> result['merge_rules'][0][1]
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256
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>>> result['vocab'][_]
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b'e '
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```
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Notice how the value from the first statement gets used as part of a `dict`
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access.
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[source](https://docs.python.org/3/tutorial/introduction.html#numbers)
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