github.com/zebozhuang/go@v0.0.0-20200207033046-f8a98f6f5c5d/src/plugin/plugin.go (about)

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package plugin implements loading and symbol resolution of Go plugins.
     6  //
     7  // A plugin is a Go main package with exported functions and variables that
     8  // has been built with:
     9  //
    10  //	go build -buildmode=plugin
    11  //
    12  // When a plugin is first opened, the init functions of all packages not
    13  // already part of the program are called. The main function is not run.
    14  // A plugin is only initialized once, and cannot be closed.
    15  //
    16  // The plugin support is currently incomplete, only supports Linux,
    17  // and has known bugs. Please report any issues.
    18  package plugin
    19  
    20  // Plugin is a loaded Go plugin.
    21  type Plugin struct {
    22  	pluginpath string
    23  	loaded     chan struct{} // closed when loaded
    24  	syms       map[string]interface{}
    25  }
    26  
    27  // Open opens a Go plugin.
    28  // If a path has already been opened, then the existing *Plugin is returned.
    29  // It is safe for concurrent use by multiple goroutines.
    30  func Open(path string) (*Plugin, error) {
    31  	return open(path)
    32  }
    33  
    34  // Lookup searches for a symbol named symName in plugin p.
    35  // A symbol is any exported variable or function.
    36  // It reports an error if the symbol is not found.
    37  // It is safe for concurrent use by multiple goroutines.
    38  func (p *Plugin) Lookup(symName string) (Symbol, error) {
    39  	return lookup(p, symName)
    40  }
    41  
    42  // A Symbol is a pointer to a variable or function.
    43  //
    44  // For example, a plugin defined as
    45  //
    46  //	package main
    47  //
    48  //	import "fmt"
    49  //
    50  //	var V int
    51  //
    52  //	func F() { fmt.Printf("Hello, number %d\n", V) }
    53  //
    54  // may be loaded with the Open function and then the exported package
    55  // symbols V and F can be accessed
    56  //
    57  //	p, err := plugin.Open("plugin_name.so")
    58  //	if err != nil {
    59  //		panic(err)
    60  //	}
    61  //	v, err := p.Lookup("V")
    62  //	if err != nil {
    63  //		panic(err)
    64  //	}
    65  //	f, err := p.Lookup("F")
    66  //	if err != nil {
    67  //		panic(err)
    68  //	}
    69  //	*v.(*int) = 7
    70  //	f.(func())() // prints "Hello, number 7"
    71  type Symbol interface{}