Pointers vs Values
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-1
I'm a bit wondering why the following code does work:
var serverStartedTime time.Time // Holds the time since the server is started.
type ServerInformation struct
Uptime ServerUptimeInformation `json:"uptime"`
type ServerUptimeInformation struct
Hours int64 `json:"hours"`
Minutes int64 `json:"minutes"`
Seconds int64 `json:"seconds"`
NanoSeconds int64 `json:"nanoSeconds"`
func main()
serverStartedTime = time.Now()
http.HandleFunc("/api/v1/health", getHealthHandler)
log.Fatal(http.ListenAndServe(":8000", nil))
func handler(writer http.ResponseWriter, request *http.Request)
fmt.Fprintf(writer, "URL.Path = %qn", request.URL.Path)
func getHealthHandler(writer http.ResponseWriter, request *http.Request)
serverUptime := time.Now().Sub(serverStartedTime)
hours := int64(serverUptime.Hours())
minutes := int64(serverUptime.Minutes()) - (hours * 60)
seconds := int64(serverUptime.Seconds()) - (hours * 60) - (minutes * 60)
nanoSeconds := int64(serverUptime.Nanoseconds()) - (hours * 60) - (minutes * 60) - (seconds * 1000000000)
serverInformation := ServerInformation
ServerUptimeInformation
hours, minutes, seconds, nanoSeconds,
,
returnJSON(writer, serverInformation)
func returnJSON(writer http.ResponseWriter, data ...interface)
dataJSON, marshalError := json.Marshal(data)
if marshalError != nil
writer.WriteHeader(http.StatusInternalServerError)
else
writer.WriteHeader(http.StatusOK)
writer.Header().Set("Content-Type", "application/json")
writer.Write(dataJSON)
By default Go copies parameters that are provided to methods.
So, the HTTP handler for '/api/v1/health' does take a writer and we pass it to the returnJSON method.
So, this method does receives a copy on which it writes.
How does it come that in my browser, I do see the response?
I didn't expected that since the writer is being copied.
go
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
add a comment |
-1
I'm a bit wondering why the following code does work:
var serverStartedTime time.Time // Holds the time since the server is started.
type ServerInformation struct
Uptime ServerUptimeInformation `json:"uptime"`
type ServerUptimeInformation struct
Hours int64 `json:"hours"`
Minutes int64 `json:"minutes"`
Seconds int64 `json:"seconds"`
NanoSeconds int64 `json:"nanoSeconds"`
func main()
serverStartedTime = time.Now()
http.HandleFunc("/api/v1/health", getHealthHandler)
log.Fatal(http.ListenAndServe(":8000", nil))
func handler(writer http.ResponseWriter, request *http.Request)
fmt.Fprintf(writer, "URL.Path = %qn", request.URL.Path)
func getHealthHandler(writer http.ResponseWriter, request *http.Request)
serverUptime := time.Now().Sub(serverStartedTime)
hours := int64(serverUptime.Hours())
minutes := int64(serverUptime.Minutes()) - (hours * 60)
seconds := int64(serverUptime.Seconds()) - (hours * 60) - (minutes * 60)
nanoSeconds := int64(serverUptime.Nanoseconds()) - (hours * 60) - (minutes * 60) - (seconds * 1000000000)
serverInformation := ServerInformation
ServerUptimeInformation
hours, minutes, seconds, nanoSeconds,
,
returnJSON(writer, serverInformation)
func returnJSON(writer http.ResponseWriter, data ...interface)
dataJSON, marshalError := json.Marshal(data)
if marshalError != nil
writer.WriteHeader(http.StatusInternalServerError)
else
writer.WriteHeader(http.StatusOK)
writer.Header().Set("Content-Type", "application/json")
writer.Write(dataJSON)
By default Go copies parameters that are provided to methods.
So, the HTTP handler for '/api/v1/health' does take a writer and we pass it to the returnJSON method.
So, this method does receives a copy on which it writes.
How does it come that in my browser, I do see the response?
I didn't expected that since the writer is being copied.
go
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
2
I don't understand what you're asking. Your title mentions pointers and values. Your body has a large block of code, and then your question is "Why do I see a response?" Please narrow your question down drastically, and include only relevant code. What is your specific question about pointers and values?
– Flimzy
Nov 16 '18 at 12:40
The question here is why I do see a value since the writer is copied over to a new method.
– Complexity
Nov 16 '18 at 12:47
add a comment |
-1
-1
-1
I'm a bit wondering why the following code does work:
var serverStartedTime time.Time // Holds the time since the server is started.
type ServerInformation struct
Uptime ServerUptimeInformation `json:"uptime"`
type ServerUptimeInformation struct
Hours int64 `json:"hours"`
Minutes int64 `json:"minutes"`
Seconds int64 `json:"seconds"`
NanoSeconds int64 `json:"nanoSeconds"`
func main()
serverStartedTime = time.Now()
http.HandleFunc("/api/v1/health", getHealthHandler)
log.Fatal(http.ListenAndServe(":8000", nil))
func handler(writer http.ResponseWriter, request *http.Request)
fmt.Fprintf(writer, "URL.Path = %qn", request.URL.Path)
func getHealthHandler(writer http.ResponseWriter, request *http.Request)
serverUptime := time.Now().Sub(serverStartedTime)
hours := int64(serverUptime.Hours())
minutes := int64(serverUptime.Minutes()) - (hours * 60)
seconds := int64(serverUptime.Seconds()) - (hours * 60) - (minutes * 60)
nanoSeconds := int64(serverUptime.Nanoseconds()) - (hours * 60) - (minutes * 60) - (seconds * 1000000000)
serverInformation := ServerInformation
ServerUptimeInformation
hours, minutes, seconds, nanoSeconds,
,
returnJSON(writer, serverInformation)
func returnJSON(writer http.ResponseWriter, data ...interface)
dataJSON, marshalError := json.Marshal(data)
if marshalError != nil
writer.WriteHeader(http.StatusInternalServerError)
else
writer.WriteHeader(http.StatusOK)
writer.Header().Set("Content-Type", "application/json")
writer.Write(dataJSON)
By default Go copies parameters that are provided to methods.
So, the HTTP handler for '/api/v1/health' does take a writer and we pass it to the returnJSON method.
So, this method does receives a copy on which it writes.
How does it come that in my browser, I do see the response?
I didn't expected that since the writer is being copied.
go
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
I'm a bit wondering why the following code does work:
var serverStartedTime time.Time // Holds the time since the server is started.
type ServerInformation struct
Uptime ServerUptimeInformation `json:"uptime"`
type ServerUptimeInformation struct
Hours int64 `json:"hours"`
Minutes int64 `json:"minutes"`
Seconds int64 `json:"seconds"`
NanoSeconds int64 `json:"nanoSeconds"`
func main()
serverStartedTime = time.Now()
http.HandleFunc("/api/v1/health", getHealthHandler)
log.Fatal(http.ListenAndServe(":8000", nil))
func handler(writer http.ResponseWriter, request *http.Request)
fmt.Fprintf(writer, "URL.Path = %qn", request.URL.Path)
func getHealthHandler(writer http.ResponseWriter, request *http.Request)
serverUptime := time.Now().Sub(serverStartedTime)
hours := int64(serverUptime.Hours())
minutes := int64(serverUptime.Minutes()) - (hours * 60)
seconds := int64(serverUptime.Seconds()) - (hours * 60) - (minutes * 60)
nanoSeconds := int64(serverUptime.Nanoseconds()) - (hours * 60) - (minutes * 60) - (seconds * 1000000000)
serverInformation := ServerInformation
ServerUptimeInformation
hours, minutes, seconds, nanoSeconds,
,
returnJSON(writer, serverInformation)
func returnJSON(writer http.ResponseWriter, data ...interface)
dataJSON, marshalError := json.Marshal(data)
if marshalError != nil
writer.WriteHeader(http.StatusInternalServerError)
else
writer.WriteHeader(http.StatusOK)
writer.Header().Set("Content-Type", "application/json")
writer.Write(dataJSON)
By default Go copies parameters that are provided to methods.
So, the HTTP handler for '/api/v1/health' does take a writer and we pass it to the returnJSON method.
So, this method does receives a copy on which it writes.
How does it come that in my browser, I do see the response?
I didn't expected that since the writer is being copied.
go
go
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
edited Nov 16 '18 at 12:39
Flimzy
40.6k1367101
40.6k1367101
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
asked Nov 16 '18 at 12:37
ComplexityComplexity
3,24522157
3,24522157
2
I don't understand what you're asking. Your title mentions pointers and values. Your body has a large block of code, and then your question is "Why do I see a response?" Please narrow your question down drastically, and include only relevant code. What is your specific question about pointers and values?
– Flimzy
Nov 16 '18 at 12:40
The question here is why I do see a value since the writer is copied over to a new method.
– Complexity
Nov 16 '18 at 12:47
add a comment |
2
I don't understand what you're asking. Your title mentions pointers and values. Your body has a large block of code, and then your question is "Why do I see a response?" Please narrow your question down drastically, and include only relevant code. What is your specific question about pointers and values?
– Flimzy
Nov 16 '18 at 12:40
The question here is why I do see a value since the writer is copied over to a new method.
– Complexity
Nov 16 '18 at 12:47
2
2
I don't understand what you're asking. Your title mentions pointers and values. Your body has a large block of code, and then your question is "Why do I see a response?" Please narrow your question down drastically, and include only relevant code. What is your specific question about pointers and values?
– Flimzy
Nov 16 '18 at 12:40
I don't understand what you're asking. Your title mentions pointers and values. Your body has a large block of code, and then your question is "Why do I see a response?" Please narrow your question down drastically, and include only relevant code. What is your specific question about pointers and values?
– Flimzy
Nov 16 '18 at 12:40
The question here is why I do see a value since the writer is copied over to a new method.
– Complexity
Nov 16 '18 at 12:47
The question here is why I do see a value since the writer is copied over to a new method.
– Complexity
Nov 16 '18 at 12:47
add a comment |
1 Answer
1
active
oldest
votes
3
You think that ResponseWriter is a struct, but it is an interface.
Every time you send writer http.ResponseWriter into your method you send pointer to struct that implements that interface.
Execute this line to see actual type:
fmt.Printf("%Tn", writer)
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
That makes sense. Thanks for the clarification.
– Complexity
Nov 16 '18 at 13:06
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
3
You think that ResponseWriter is a struct, but it is an interface.
Every time you send writer http.ResponseWriter into your method you send pointer to struct that implements that interface.
Execute this line to see actual type:
fmt.Printf("%Tn", writer)
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
That makes sense. Thanks for the clarification.
– Complexity
Nov 16 '18 at 13:06
add a comment |
3
You think that ResponseWriter is a struct, but it is an interface.
Every time you send writer http.ResponseWriter into your method you send pointer to struct that implements that interface.
Execute this line to see actual type:
fmt.Printf("%Tn", writer)
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
That makes sense. Thanks for the clarification.
– Complexity
Nov 16 '18 at 13:06
add a comment |
3
3
3
You think that ResponseWriter is a struct, but it is an interface.
Every time you send writer http.ResponseWriter into your method you send pointer to struct that implements that interface.
Execute this line to see actual type:
fmt.Printf("%Tn", writer)
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
You think that ResponseWriter is a struct, but it is an interface.
Every time you send writer http.ResponseWriter into your method you send pointer to struct that implements that interface.
Execute this line to see actual type:
fmt.Printf("%Tn", writer)
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
answered Nov 16 '18 at 12:55
Dmitry HarnitskiDmitry Harnitski
3,86311834
3,86311834
That makes sense. Thanks for the clarification.
– Complexity
Nov 16 '18 at 13:06
add a comment |
That makes sense. Thanks for the clarification.
– Complexity
Nov 16 '18 at 13:06
That makes sense. Thanks for the clarification.
– Complexity
Nov 16 '18 at 13:06
That makes sense. Thanks for the clarification.
– Complexity
Nov 16 '18 at 13:06
add a comment |
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2
I don't understand what you're asking. Your title mentions pointers and values. Your body has a large block of code, and then your question is "Why do I see a response?" Please narrow your question down drastically, and include only relevant code. What is your specific question about pointers and values?
– Flimzy
Nov 16 '18 at 12:40
The question here is why I do see a value since the writer is copied over to a new method.
– Complexity
Nov 16 '18 at 12:47