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18 lines
930 B
Markdown
18 lines
930 B
Markdown
# Command
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## Purpose
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To encapsulate invocation and decoupling.
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We have an Invoker and a Receiver. This pattern uses a "Command" to delegate the method call against the Receiver and presents the same method "execute".
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Therefore, the Invoker just knows to call "execute" to process the Command of the client. The Receiver is decoupled from the Invoker.
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The second aspect of this pattern is the undo(), which undoes the method execute().
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Command can also be aggregated to combine more complex commands with minimum copy-paste and relying on composition over inheritance.
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## Examples
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* A text editor : all events are Command which can be undone, stacked and saved.
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* Symfony2: SF2 Commands that can be run from the CLI are built with just the Command pattern in mind
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* big CLI tools use subcommands to distribute various tasks and pack them in "modules", each of these can be implemented with the Command pattern (e.g. vagrant)
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