Add gather method in future chainer

[codecov-commenter]

Codecov Report

Patch coverage: 96.37% and project coverage change: -1.03 :warning:

Comparison is base (c7f00ea) 98.43% compared to head (bbe3839) 97.41%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #10 +/- ## ========================================== - Coverage 98.43% 97.41% -1.03% ========================================== Files 10 12 +2 Lines 256 387 +131 ========================================== + Hits 252 377 +125 - Misses 4 10 +6 ``` | [Impacted Files](https://app.codecov.io/gh/KYLChiu/the-big-learning-repo/pull/10?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Kelvin+Chiu) | Coverage Δ | | |---|---|---| | [cpp/kc\_utils/data\_structures/linked\_list.hpp](https://app.codecov.io/gh/KYLChiu/the-big-learning-repo/pull/10?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Kelvin+Chiu#diff-Y3BwL2tjX3V0aWxzL2RhdGFfc3RydWN0dXJlcy9saW5rZWRfbGlzdC5ocHA=) | `91.66% <91.66%> (ø)` | | | [cpp/kc\_utils/concurrency/future\_chainer.hpp](https://app.codecov.io/gh/KYLChiu/the-big-learning-repo/pull/10?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Kelvin+Chiu#diff-Y3BwL2tjX3V0aWxzL2NvbmN1cnJlbmN5L2Z1dHVyZV9jaGFpbmVyLmhwcA==) | `93.10% <92.00%> (-6.90%)` | :arrow_down: | | [cpp/sandbox/data\_structures\_test.cpp](https://app.codecov.io/gh/KYLChiu/the-big-learning-repo/pull/10?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Kelvin+Chiu#diff-Y3BwL3NhbmRib3gvZGF0YV9zdHJ1Y3R1cmVzX3Rlc3QuY3Bw) | `100.00% <100.00%> (ø)` | | | [cpp/sandbox/future\_chainer\_test.cpp](https://app.codecov.io/gh/KYLChiu/the-big-learning-repo/pull/10?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Kelvin+Chiu#diff-Y3BwL3NhbmRib3gvZnV0dXJlX2NoYWluZXJfdGVzdC5jcHA=) | `96.92% <100.00%> (+1.92%)` | :arrow_up: | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/KYLChiu/the-big-learning-repo/pull/10/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Kelvin+Chiu)

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[ccjeremylo]

Can you add some context...no idea what I am reading

You are implementing a linked list right? what is a future chainer?

[KYLChiu]

Can you add some context...no idea what I am reading

You are implementing a linked list right? what is a future chainer?

Linked list impl is kinda bad atm tbh, will update later...

Future is a structure representing a result you'll get later on (from an async operation, e.g. from another thread)... future chaining is just some convenience method which lets you link these futures into one chain - so that once the prior future is ready, we can (immediately) run a continuation function on the result obtained once prior future finishes evaluation. If you look at the comments there are some examples. The original idea comes from Javascript A* promises but that stuff is too tedious to implement.

[ccjeremylo]

Seems I already approved this, but I guess need to re-approve after you pushed again?

or are we just missing @claudiayip 's approve for this PR?

[ccjeremylo]

Seems I already approved this, but I guess need to re-approve after you pushed again?

or are we just missing @claudiayip 's approve for this PR?

Was being dumb - think I approved it now

[ccjeremylo]

Can you add some context...no idea what I am reading You are implementing a linked list right? what is a future chainer?

Linked list impl is kinda bad atm tbh, will update later...

Future is a structure representing a result you'll get later on (from an async operation, e.g. from another thread)... future chaining is just some convenience method which lets you link these futures into one chain - so that once the prior future is ready, we can (immediately) run a continuation function on the result obtained once prior future finishes evaluation. If you look at the comments there are some examples. The original idea comes from Javascript A* promises but that stuff is too tedious to implement.

Sounds so complicated...I guess the examples are in the test file?