subdict.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  // Test cases where a main dictionary is needed inside a generic function/method, because
     8  // we are calling a method on a fully-instantiated type or a fully-instantiated function.
     9  // (probably not common situations, of course)
    10  
    11  package main
    12  
    13  import (
    14  	"fmt"
    15  )
    16  
    17  type C comparable
    18  
    19  type value[T C] struct {
    20  	val T
    21  }
    22  
    23  func (v *value[T]) test(def T) bool {
    24  	return (v.val == def)
    25  }
    26  
    27  func (v *value[T]) get(def T) T {
    28  	var c value[int]
    29  	if c.test(32) {
    30  		return def
    31  	} else if v.test(def) {
    32  		return def
    33  	} else {
    34  		return v.val
    35  	}
    36  }
    37  
    38  func main() {
    39  	var s value[string]
    40  	if got, want := s.get("ab"), ""; got != want {
    41  		panic(fmt.Sprintf("get() == %d, want %d", got, want))
    42  	}
    43  }
    44
View as plain text