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_.memoize: Show default hash function in Docs #137

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DTrejo opened this issue Mar 3, 2011 · 1 comment
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_.memoize: Show default hash function in Docs #137

DTrejo opened this issue Mar 3, 2011 · 1 comment
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enhancement fixed

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@DTrejo
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DTrejo commented Mar 3, 2011

After playing around with _.memoize, I see that the default hash function is

// Note that _.memoize hashes only the first argument by default.
function(arg1) {
  return arg1;
}

It would be cool if the docs mentioned this.

I'll send a pull request when I have a moment to fork+edit.

Thanks for making a super useful library!
-David
@jashkenas
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Sure thing:

d71f480

albemuth pushed a commit to albemuth/underscore that referenced this issue May 4, 2011
@jashkenas
Issue jashkenas#137. Docs for memoize.
d71f480
roryokane added a commit to roryokane/underscore that referenced this issue Sep 17, 2013
@roryokane
Document in _.memoize why _.identity is a first-argument hasher
d9e1495 
With a comment, document the nonobvious behavior of _.identity in this context.

I wrote this comment to accompany the following sentence from [the current docs for `_.memoize`](http://documentcloud.github.io/underscore/#memoize):

> The default **hashFunction** just uses the first argument to the memoized function as the key.

I looked in the code, but couldn’t see how that was the case. The code quoted in [Issue jashkenas#137](jashkenas#137) was no longer there. I wondered if that sentence in the documentation was out-of-date. It took me a while to notice that the use of `apply` over `call` changed `_.identity` from returning `arguments` to returning the first argument.
@roryokane roryokane mentioned this issue Sep 17, 2013
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@jashkenas @DTrejo