issue49512.go

     1  // run
     2  
     3  // Copyright 2021 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  package main
     8  
     9  type S struct{
    10  	m1Called, m2Called bool
    11  }
    12  
    13  func (s *S) M1(int) (int, int) {
    14  	s.m1Called = true
    15  	return 0, 0
    16  }
    17  
    18  func (s *S) M2(int) (int, int) {
    19  	s.m2Called = true
    20  	return 0, 0
    21  }
    22  
    23  type C struct {
    24  	calls []func(int) (int, int)
    25  }
    26  
    27  func makeC() Funcs {
    28  	return &C{}
    29  }
    30  
    31  func (c *C) Add(fn func(int) (int, int)) Funcs {
    32  	c.calls = append(c.calls, fn)
    33  	return c
    34  }
    35  
    36  func (c *C) Call() {
    37  	for _, fn := range c.calls {
    38  		fn(0)
    39  	}
    40  }
    41  
    42  type Funcs interface {
    43  	Add(func(int) (int, int)) Funcs
    44  	Call()
    45  }
    46  
    47  func main() {
    48  	s := &S{}
    49  	c := makeC().Add(s.M1).Add(s.M2)
    50  	c.Call()
    51  	if !s.m1Called || !s.m2Called {
    52  		panic("missed method call")
    53  	}
    54  }
    55
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