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Simplify pattern match for patch_preflight
#1671
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This one is easier to explain if you format the pattern match a bit:
```elixir
case { passed_label, no_error_status, no_waiting_status, no_unset_status, passed_review, code_owners_approved, passed_up_to_date_review} do
{ true , true , true , true , :sufficient , true , :sufficient } -> {:ok, toml.max_batch_size}
{ false , _ , _ , _ , _ , _ , _ } -> {:error, :blocked_labels}
{ _ , _ , _ , _ , :insufficient, _ , _ } -> {:error, :insufficient_approvals}
{ _ , _ , _ , _ , :failed , _ , _ } -> {:error, :blocked_review}
{ _ , _ , _ , _ , _ , false , _ } -> {:error, :missing_code_owner_approval}
{ _ , false , _ , _ , _ , _ , _ } -> {:error, :pr_status}
{ true , true , false , _ , :sufficient , true , _ } -> :waiting
{ true , true , _ , false , :sufficient , true , _ } -> :waiting
{ _ , _ , _ , _ , :sufficient , _ , :insufficient } -> {:error, :insufficient_up_to_date_approvals}
end
```
Notice how after the second case of the pattern match the first value
must necessarily be `true`, so you can convert those to wildcard
pattern matches:
```elixir
case { passed_label, no_error_status, no_waiting_status, no_unset_status, passed_review, code_owners_approved, passed_up_to_date_review} do
{ true , true , true , true , :sufficient , true , :sufficient } -> {:ok, toml.max_batch_size}
{ false , _ , _ , _ , _ , _ , _ } -> {:error, :blocked_labels}
{ _ , _ , _ , _ , :insufficient, _ , _ } -> {:error, :insufficient_approvals}
{ _ , _ , _ , _ , :failed , _ , _ } -> {:error, :blocked_review}
{ _ , _ , _ , _ , _ , false , _ } -> {:error, :missing_code_owner_approval}
{ _ , false , _ , _ , _ , _ , _ } -> {:error, :pr_status}
{ _ , true , false , _ , :sufficient , true , _ } -> :waiting
{ _ , true , _ , false , :sufficient , true , _ } -> :waiting
{ _ , _ , _ , _ , :sufficient , _ , :insufficient } -> {:error, :insufficient_up_to_date_approvals}
end
# ↑ s/true/_/ after the first false
```
If you keep repeating this process (of replacing pattern matches that
are guaranteed to succeed with wildcards) then you get this sequence of
pattern matches:
```elixir
case { passed_label, no_error_status, no_waiting_status, no_unset_status, passed_review, code_owners_approved, passed_up_to_date_review} do
{ true , true , true , true , :sufficient , true , :sufficient } -> {:ok, toml.max_batch_size}
{ false , _ , _ , _ , _ , _ , _ } -> {:error, :blocked_labels}
{ _ , _ , _ , _ , :insufficient, _ , _ } -> {:error, :insufficient_approvals}
{ _ , _ , _ , _ , :failed , _ , _ } -> {:error, :blocked_review}
{ _ , _ , _ , _ , _ , false , _ } -> {:error, :missing_code_owner_approval}
{ _ , false , _ , _ , _ , _ , _ } -> {:error, :pr_status}
{ _ , _ , false , _ , _ , _ , _ } -> :waiting
{ _ , _ , _ , false , _ , _ , _ } -> :waiting
{ _ , _ , _ , _ , _ , _ , :insufficient } -> {:error, :insufficient_up_to_date_approvals}
end
```
… which is clearer (IMO) because now it basically reads as:
- either all conditions pass or …
- one of the conditions individually fails
… which makes it more clear that this sequence of pattern matches is
exhaustive.
notriddle
approved these changes
Jun 1, 2023
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This one is easier to explain if you format the pattern match a bit:
Notice how after the second case of the pattern match the first value must necessarily be
true, so you can convert those to wildcard pattern matches:If you keep repeating this process (of replacing pattern matches that are guaranteed to succeed with wildcards) then you get this sequence of pattern matches:
… which is clearer (IMO) because now it basically reads as:
… which makes it more clear that this sequence of pattern matches is exhaustive.