3e31ee9455
With the recent merging of embedded package imports and the entry CLI package, it is now possible for users to build in mcl code into a single binary. This additional permission makes it explicitly clear that this is permitted to make it easier for those users. The condition is phrased so that the terms can be "patched" by the original author if it's necessary for the project. For example, if the name of the language (mcl) changes, has a differently named new version, someone finds a phrasing improvement or a legal loophole, or for some other reasonable circumstance. Now go write some beautiful embedded tools!
98 lines
4.1 KiB
Go
98 lines
4.1 KiB
Go
// Mgmt
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// Copyright (C) 2013-2024+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it 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
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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// Additional permission under GNU GPL version 3 section 7
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//
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// If you modify this program, or any covered work, by linking or combining it
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// with embedded mcl code and modules (and that the embedded mcl code and
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// modules which link with this program, contain a copy of their source code in
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// the authoritative form) containing parts covered by the terms of any other
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// license, the licensors of this program grant you additional permission to
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// convey the resulting work. Furthermore, the licensors of this program grant
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// the original author, James Shubin, additional permission to update this
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// additional permission if he deems it necessary to achieve the goals of this
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// additional permission.
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package engine
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import (
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"fmt"
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)
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// ReversibleRes is an interface that a resource can implement if it wants to
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// have some resource run when it disappears. A disappearance happens when a
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// resource is defined in one instance of the graph, and is gone in the
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// subsequent one. This is helpful for building robust programs with the engine.
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// Default implementations for most of the methods declared in this interface
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// can be obtained for your resource by anonymously adding the traits.Reversible
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// struct to your resource implementation.
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type ReversibleRes interface {
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Res
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// ReversibleMeta lets you get or set meta params for the reversible
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// trait.
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ReversibleMeta() *ReversibleMeta
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// SetReversibleMeta lets you set all of the meta params for the
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// reversible trait in a single call.
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SetReversibleMeta(*ReversibleMeta)
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// Reversed returns the "reverse" or "reciprocal" resource. This is used
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// to "clean" up after a previously defined resource has been removed.
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// Interestingly, this could return the core Res interface instead of a
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// ReversibleRes, because there is no requirement that the reverse of a
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// Res be the same kind of Res, and the reverse might not be reversible!
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// However, in practice, it's nice to use some of the Reversible meta
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// params in the built value, so keep things simple and have this be a
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// reversible res. The Res itself doesn't have to implement Reversed()
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// in a meaningful way, it can just return nil and it will get ignored.
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Reversed() (ReversibleRes, error)
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}
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// ReversibleMeta provides some parameters specific to reversible resources.
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type ReversibleMeta struct {
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// Disabled specifies that reversing should be disabled for this
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// resource.
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Disabled bool
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// Reversal specifies that the resource was built from a reversal. This
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// must be set if the resource was built by a reversal.
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Reversal bool
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// Overwrite specifies that we should overwrite any existing stored
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// reversible resource if one that is pending already exists. If this is
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// false, and a resource with the same name and kind exists, then this
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// will cause an error.
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Overwrite bool
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// TODO: add options here, including whether to reverse edges, etc...
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}
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// Cmp compares two ReversibleMeta structs and determines if they're equivalent.
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func (obj *ReversibleMeta) Cmp(rm *ReversibleMeta) error {
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if obj.Disabled != rm.Disabled {
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return fmt.Errorf("values for Disabled are different")
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}
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if obj.Reversal != rm.Reversal { // TODO: do we want to compare these?
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return fmt.Errorf("values for Reversal are different")
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}
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if obj.Overwrite != rm.Overwrite {
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return fmt.Errorf("values for Overwrite are different")
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}
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return nil
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}
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