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Source file src/runtime/example_test.go

Documentation: runtime

     1  // Copyright 2017 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 runtime_test
     6  
     7  import (
     8  	"fmt"
     9  	"runtime"
    10  	"strings"
    11  )
    12  
    13  func ExampleFrames() {
    14  	c := func() {
    15  		// Ask runtime.Callers for up to 10 pcs, including runtime.Callers itself.
    16  		pc := make([]uintptr, 10)
    17  		n := runtime.Callers(0, pc)
    18  		if n == 0 {
    19  			// No pcs available. Stop now.
    20  			// This can happen if the first argument to runtime.Callers is large.
    21  			return
    22  		}
    23  
    24  		pc = pc[:n] // pass only valid pcs to runtime.CallersFrames
    25  		frames := runtime.CallersFrames(pc)
    26  
    27  		// Loop to get frames.
    28  		// A fixed number of pcs can expand to an indefinite number of Frames.
    29  		for {
    30  			frame, more := frames.Next()
    31  			// To keep this example's output stable
    32  			// even if there are changes in the testing package,
    33  			// stop unwinding when we leave package runtime.
    34  			if !strings.Contains(frame.File, "runtime/") {
    35  				break
    36  			}
    37  			fmt.Printf("- more:%v | %s\n", more, frame.Function)
    38  			if !more {
    39  				break
    40  			}
    41  		}
    42  	}
    43  
    44  	b := func() { c() }
    45  	a := func() { b() }
    46  
    47  	a()
    48  	// Output:
    49  	// - more:true | runtime.Callers
    50  	// - more:true | runtime_test.ExampleFrames.func1
    51  	// - more:true | runtime_test.ExampleFrames.func2
    52  	// - more:true | runtime_test.ExampleFrames.func3
    53  	// - more:true | runtime_test.ExampleFrames
    54  }
    55  

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