Stencil generates specialized versions of Go packages by replacing types. This is a prototype of this proposal. It will have bugs and only supports a subset of the features in the proposal.
Given a package with an interface A, stencil can generate a new package with all uses of A replaced by int (or any other type).
The generated package is stored in the closest vendor directory of the repo. If no such directory exists, one is created.
Download stencil using
go get -u github.com/sridharv/stencil
Install with
go install github.com/sridharv/stencil/cmd/stencil
Detailed documentation is at
Install stencil as shown above. Then create a package to act as a stencil. Let's create a generic Sum method.
Create $GOPATH/src/example/stencil/math/math.go (or a package of your choice) containing
package math
func Sum(n...float64) float64 {
var r float64
for _, v := range n {
r += v
}
return r
}
Now use it to compute the sum of ints by using stencil to replace float64 with int.
Create $GOPATH/src/example/usestencil/main.go (or another package of your choice) containing
package main
//go:generate stencil
import (
"fmt"
int_math "example/stencil/math/float64/int"
)
// PrintIntSum prints the sum of all elements of v to stdout.
func main() {
ints := []int{1, 2, 3, 4, 5}
fmt.Println("Sum of", v, "=", int_math.Sum(ints...))
}
Now run
# Or the path to the main package you created
cd $GOPATH/src/example/usestencil/
and then
go generate
Take a look at $GOPATH/src/example/usestencil/. It will have a vendor directory with a specialised version of
example/stencil/math. You can now build and run the example with
go run main.go
A few useful packages that lend themselves to being used with stencil.
github.com/sridharv/stencil/std/num- Max, Min and Sum for numbers.github.com/sridharv/stencil/std/slice- Slice utilities.
Stencil is available under the Apache License. See the LICENSE file for details.
Pull requests are always welcome! Please ensure any changes you send have an accompanying test case.
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