Files
mgmt/lang/core/math/fortytwo_func.go
James Shubin 415e22abe2 lang: core, funcs, types: Add ctx to simple func
Plumb through the standard context.Context so that a function can be
cancelled if someone requests this. It makes it less awkward to write
simple functions that might depend on io or network access.
2024-05-09 19:25:46 -04:00

83 lines
3.0 KiB
Go

// Mgmt
// Copyright (C) 2013-2024+ James Shubin and the project contributors
// Written by James Shubin <james@shubin.ca> and the project contributors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
// Additional permission under GNU GPL version 3 section 7
//
// If you modify this program, or any covered work, by linking or combining it
// with embedded mcl code and modules (and that the embedded mcl code and
// modules which link with this program, contain a copy of their source code in
// the authoritative form) containing parts covered by the terms of any other
// license, the licensors of this program grant you additional permission to
// convey the resulting work. Furthermore, the licensors of this program grant
// the original author, James Shubin, additional permission to update this
// additional permission if he deems it necessary to achieve the goals of this
// additional permission.
package coremath
import (
"context"
"fmt"
"github.com/purpleidea/mgmt/lang/funcs/simplepoly"
"github.com/purpleidea/mgmt/lang/types"
)
func init() {
typInt := types.NewType("func() int")
typFloat := types.NewType("func() float")
simplepoly.ModuleRegister(ModuleName, "fortytwo", []*types.FuncValue{
{
T: typInt,
V: fortyTwo(typInt), // generate the correct function here
},
{
T: typFloat,
V: fortyTwo(typFloat),
},
})
}
// fortyTwo is a helper function to build the correct function for the desired
// signature, because the simplepoly API doesn't tell the implementing function
// what its signature should be! In the next version of this API, we could pass
// in a sig field, like how we demonstrate in the implementation of FortyTwo. If
// the API doesn't change, then this is an example of how to build this as a
// wrapper.
func fortyTwo(sig *types.Type) func(context.Context, []types.Value) (types.Value, error) {
return func(ctx context.Context, input []types.Value) (types.Value, error) {
return FortyTwo(sig, input)
}
}
// FortyTwo returns 42 as either an int or a float. This is not especially
// useful, but was built for a fun test case of a simple poly function with two
// different return types, but no input args.
func FortyTwo(sig *types.Type, input []types.Value) (types.Value, error) {
if sig.Out.Kind == types.KindInt {
return &types.IntValue{
V: 42,
}, nil
}
if sig.Out.Kind == types.KindFloat {
return &types.FloatValue{
V: 42.0,
}, nil
}
return nil, fmt.Errorf("unknown output type: %+v", sig.Out)
}