69 lines
1.4 KiB
Markdown
69 lines
1.4 KiB
Markdown
# Caller
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Package caller is used to dynamically call functions with data unmarshalled
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into the functions' first argument. Its main purpose is to hide common
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unmarshalling code from each function implementation thus reducing
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boilerplate and making package interaction code sexier.
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[Documentation](https://godoc.org/github.com/localhots/uberdaemon/caller)
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### Example
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```go
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package main
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import (
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"log"
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"github.com/localhots/uberdaemon/caller"
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"github.com/path/to/package/messenger"
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)
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type PriceUpdate struct {
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Product string `json:"product"`
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Amount float32 `json:"amount"`
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}
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func main() {
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messenger.Subscribe("ProductPriceUpdates", func(p PriceUpdate) {
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log.Printf("Price for %q is now $%.2f", p.Product, p.Amount)
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})
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messenger.Deliver()
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}
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```
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Support code:
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```go
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package messenger
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import (
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"github.com/localhots/uberdaemon/caller"
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)
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type item struct {
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topic string
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payload []byte
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}
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var queue <-chan item
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var subscriptions = make(map[string][]*caller.Caller)
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func Subscribe(topic string, callback interface{}) {
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c, err := caller.New(processMessage)
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if err != nil {
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panic(err)
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}
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subcriptions[topic] = append(subcriptions[topic], c)
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}
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func Deliver() {
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for itm := range queue {
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for _, c := range subscriptions[itm.topic] {
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// Payload example:
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// {"product": "Paperclip", "amount": 0.01}
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c.Call(itm.payload)
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}
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}
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}
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```
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