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https://github.com/ethereum/go-ethereum.git
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ba9ab538b9
## Why this should be merged Adds default-value support to the `options` package, which could previously only create configured types from zero values. ## How this works Exposes the option-application loop as the `ApplyTo()` function and refactors `As()` to share this code path. ## How this was tested Testable example acting as a unit test.
66 lines
2 KiB
Go
66 lines
2 KiB
Go
// Copyright 2025 the libevm authors.
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//
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// The libevm additions to go-ethereum are free software: you can redistribute
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// them and/or modify them under the terms of the GNU Lesser General Public License
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// as published by the Free Software Foundation, either version 3 of the License,
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// or (at your option) any later version.
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//
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// The libevm additions are distributed in the hope that they will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
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// General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see
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// <http://www.gnu.org/licenses/>.
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package options_test
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import (
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"fmt"
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"github.com/ava-labs/libevm/libevm/options"
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)
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// config is an arbitrary type to be configured with [options.Option] values.
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// Although it can be exported, there is typically no need.
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type config struct {
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num int
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flag bool
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}
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// An Option configures an arbitrary type. Using a type alias (=) instead of a
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// completely new type is recommended as it maintains compatibility with helpers
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// such as [options.Func].
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type Option = options.Option[config]
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func WithNum(n int) Option {
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return options.Func[config](func(c *config) {
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c.num = n
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})
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}
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func WithFlag(b bool) Option {
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return options.Func[config](func(c *config) {
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c.flag = b
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})
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}
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func Example() {
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num42 := WithNum(42)
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flagOn := WithFlag(true)
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// Some IDEs and linters might complain about the redundant type parameter
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// as it can be inferred, but it makes for more readable code.
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fromZero := options.As[config](num42, flagOn)
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fmt.Printf("From zero value: %T(%+[1]v)\n", fromZero)
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fromDefault := options.ApplyTo(&config{
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num: 100,
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}, flagOn)
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fmt.Printf("Applied to default value: %T(%+[1]v)\n", fromDefault)
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// Output:
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// From zero value: *options_test.config(&{num:42 flag:true})
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// Applied to default value: *options_test.config(&{num:100 flag:true})
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}
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