Finishing up the exercise

concepts/stringers/.meta/config.json

@@ -3,5 +3,7 @@
   "authors": [
     "norbs57"
   ],
-  "contributors": []
+  "contributors": [
+    "andrerfcsantos"
+  ]
 }

concepts/stringers/about.md

@@ -10,7 +10,7 @@ type Stringer interface {
 }
 ```
 
-Types that want to implement this interface must have a `String()` method that returns a human-friendly string representation of the type. The [fmt][fmt-package] package (and many others) will look for this method to print values.
+Types that want to implement this interface must have a `String()` method that returns a human-friendly string representation of the type. The [fmt][fmt-package] package (and many others) will look for this method to format and print values.
 
 ## Example: Distances
 
@@ -23,7 +23,6 @@ type DistanceUnit int
 const (
 	Kilometer    DistanceUnit = 0
 	Mile         DistanceUnit = 1
-	NauticalMile DistanceUnit = 2
 )
 
 type Distance struct {
@@ -32,38 +31,54 @@ type Distance struct {
 } 
 ```
 
+In the example above, `Kilometer` and `Mile` ane constants of type `DistanceUnit`.
+
 These types do not implement interface `Stringer` as they lack the `String` method.
 Hence `fmt` functions will print `Distance` values using Go's "default format":
 
-```go 
-var distances = []Distance{
-	{number: 790.7, unit: Kilometer},
-	{number: 415.2, unit: Mile},
-	{number: 10_500, unit: NauticalMile},
-} 
-fmt.Println(distances)
-// Output: [{790.7 0} {415.2 1} {10500 2}]
+```go
+mileUnit := Mile
+fmt.Sprint(mileUnit)
+// => 1
+// The result is '1' because that is the underlying value of the 'Mile' contant (see contant declarations above) 
+
+dist := Distance{number: 790.7, unit: Kilometer}
+fmt.Sprint(dist)
+// => {790.7 0}
+// not a very useful output!
 ```
 
-In order to make the output more informative, we implement interface `Stringer` by adding a `String` method to each type:
+In order to make the output more informative, we implement interface `Stringer` for `DistanceUnit` and `Distance` types by adding a `String` method to each type:
 
 ```go
 func (sc DistanceUnit) String() string {
-	units := []string{"km", "mi", "nmi"}
+	units := []string{"km", "mi"}
 	return units[sc]
 }
 
 func (d Distance) String() string {
 	return fmt.Sprintf("%v %v", d.number, d.unit)
-} 
+}
 ```
 
 `fmt` package functions will call these methods when formatting `Distance` values:
 
 ```go
-fmt.Println(distances)
-// Output: [790.7 km 415.2 mi 10500 nmi]
+kmUnit := Kilometer
+kmUnit.String()
+// => km
+
+mileUnit := Mile
+mileUnit.String()
+// => mi
+
+dist := Distance{
+	number: 790.7,
+	unit: Kilometer,
+}
+dist.String()
+// => 790.7 km
 ```
 
 [stringer-interface]: https://pkg.go.dev/fmt#Stringer
-[fmt-package]: https://pkg.go.dev/fmt
+[fmt-package]: https://pkg.go.dev/fmt

concepts/stringers/introduction.md

@@ -10,7 +10,7 @@ type Stringer interface {
 }
 ```
 
-Types that want to implement this interface must have a `String()` method that returns a human-friendly string representation of the type. The [fmt][fmt-package] package (and many others) will look for this method to print values.
+Types that want to implement this interface must have a `String()` method that returns a human-friendly string representation of the type. The [fmt][fmt-package] package (and many others) will look for this method to format and print values.
 
 ## Example: Distances
 
@@ -23,7 +23,6 @@ type DistanceUnit int
 const (
 	Kilometer    DistanceUnit = 0
 	Mile         DistanceUnit = 1
-	NauticalMile DistanceUnit = 2
 )
 
 type Distance struct {
@@ -32,37 +31,53 @@ type Distance struct {
 } 
 ```
 
+In the example above, `Kilometer` and `Mile` ane constants of type `DistanceUnit`.
+
 These types do not implement interface `Stringer` as they lack the `String` method.
 Hence `fmt` functions will print `Distance` values using Go's "default format":
 
-```go 
-var distances = []Distance{
-	{number: 790.7, unit: Kilometer},
-	{number: 415.2, unit: Mile},
-	{number: 10_500, unit: NauticalMile},
-} 
-fmt.Println(distances)
-// Output: [{790.7 0} {415.2 1} {10500 2}]
+```go
+mileUnit := Mile
+fmt.Sprint(mileUnit)
+// => 1
+// The result is '1' because that is the underlying value of the 'Mile' contant (see contant declarations above) 
+
+dist := Distance{number: 790.7, unit: Kilometer}
+fmt.Sprint(dist)
+// => {790.7 0}
+// not a very useful output!
 ```
 
-In order to make the output more informative, we implement interface `Stringer` by adding a `String` method to each type:
+In order to make the output more informative, we implement interface `Stringer` for `DistanceUnit` and `Distance` types by adding a `String` method to each type:
 
 ```go
 func (sc DistanceUnit) String() string {
-	units := []string{"km", "mi", "nmi"}
+	units := []string{"km", "mi"}
 	return units[sc]
 }
 
 func (d Distance) String() string {
 	return fmt.Sprintf("%v %v", d.number, d.unit)
-} 
+}
 ```
 
 `fmt` package functions will call these methods when formatting `Distance` values:
 
 ```go
-fmt.Println(distances)
-// Output: [790.7 km 415.2 mi 10500 nmi]
+kmUnit := Kilometer
+kmUnit.String()
+// => km
+
+mileUnit := Mile
+mileUnit.String()
+// => mi
+
+dist := Distance{
+	number: 790.7,
+	unit: Kilometer,
+}
+dist.String()
+// => 790.7 km
 ```
 
 [stringer-interface]: https://pkg.go.dev/fmt#Stringer

exercises/concept/meteorology/.docs/hints.md

@@ -1,23 +1,40 @@
 # Hints
 
 ## 1. Implement the `Stringer` interface for type `TemperatureUnit`
-
-See [yourbasic.org][yourbasic-enum] for an example how to define a "enum" type with a `String` method.
+
+- The type `TemperatureUnit` is already created for you and represents a temperature unit
+- Note that there are already 2 constants created for you that are of this type: `Celsius` and `Fahrenheit`, representing a temperature in Celsius and Fahrenheit, respectively
+- Add a `String()` method to the `TemperatureUnit` type so it satisfies the `Stringer` interface. This method must return the string `"°C"` if the temperature unit is Celsius or `"°F"` if the temperature unit is Fahrenheit
 
 ## 2. Implement the `Stringer` interface for type  `Temperature` 
 
-See [yourbasic.org][yourbasic-enum] for an example how to define a "enum" type with a `String` method.
+ - Add a `String()` method to the `Temperature` type so it satisfies the `Stringer` interface
+ - The `String()` method should return a string with the numeric value for the temperature and the temperature unit separated by a space (`<temperature> <unit>`)
+ - The `Temperature` struct contains a `TemperatureUnit` and a `int`. You can use [fmt.Sprintf][sprintf] to help you format this string
+ - Since `TemperatureUnit` already implements the `Stringer` interface (from task 1), the functions of the `fmt` package like [fmt.Sprintf][sprintf] will know how to format it when you use the `%v` or `%s` [formatting verbs][fmt]
 
 ## 3. Implement the `Stringer` interface for type `SpeedUnit`
 
-See [yourbasic.org][yourbasic-enum] for an example how to define a "enum" type with a `String` method.
+- The type `SpeedUnit` is already created for you and represents a temperature unit
+- Note that there are already 2 constants created for you that are of this type: `KmPerHour` and `MilesPerHour`, representing a speed in kilometers per hour and miles per hour, respectively
+- Add a `String()` method to the `SpeedUnit` type so it satisfies the `Stringer` interface. This method must return the string `"km/h"` if the speed unit is kilometers per hour or `"mph"` if the speed unit is miles per hour.
 
 ## 4. Implement the `Stringer` interface for `Speed`
 
-See [yourbasic.org][yourbasic-enum] for an example how to define a "enum" type with a `String` method.
+ - Add a `String()` method to the `Speed` type so it satisfies the `Stringer` interface
+ - The `String()` method should return a string with the numeric value for the speed and the speed unit separated by a space (`<speed> <unit>`)
+ - The `Speed` contains a `SpeedUnit` and a `int`. You can use [fmt.Sprintf][sprintf] to help you format this string
+ - Since `TemperatureUnit` struct already implements the `Stringer` interface (from task 3), the functions of the `fmt` package like [fmt.Sprintf][sprintf] will know how to format it when you use the `%v` or `%s` [formatting verbs][fmt]
+- To insert a `%` in the final string when using [fmt.Sprintf][sprintf], use `%%` in the formatting string.
+
+## 5. Implement the `Stringer` interface for type `MeteorologyData`
+
+ - The `Speed` contains a `Temperature` and a `Speed` fields, among other fields. You can use [fmt.Sprintf][sprintf] to help you format this string
+ - The `String` method should return the meteorology data in the following format: `"<location>: <temperature>, Wind <wind_speed> at <wind_direction>, <humidity>% Humidity"`
+ - Since the `Temperature` and `Speed` types already implement the `Stringer` interface (from task 2 and 4), the functions of the `fmt` package like [fmt.Sprintf][sprintf] will know how to format it when you use the `%v` or `%s` [formatting verbs][fmt]
 
-## 5. Implement the `Stringer` interface for type `MetData`
 
-See [yourbasic.org][yourbasic-enum] for an example how to define a "enum" type with a `String` method.
-
+[fmt]: https://pkg.go.dev/fmt
+[sprint]: https://pkg.go.dev/fmt#Sprint
+[sprintf]: https://pkg.go.dev/fmt#Sprintf
 [yourbasic-enum]: https://yourbasic.org/golang/iota/#complete-enum-type-with-strings-best-practice

exercises/concept/meteorology/.docs/instructions.md

@@ -7,51 +7,121 @@ Your task is to add suitable `String` methods to all types so that they implemen
 
 ## 1. Implement the `Stringer` interface for type `TemperatureUnit`
 
-After some discussion, the team have agreed that the unit of temperature will be either `Celsius` or `Fahrenheit`. Values should be formatted as shown below: 
+After some discussion, the team have agreed that the unit of temperature will be either `Celsius` or `Fahrenheit`. Values should be formatted as shown in the examples below.
+
+Make the `TemperatureUnit` type implement the `Stringer` interface by adding a `String` method to it. This method must return the string `"°C"` if the temperature unit is Celsius or `"°F"` if the temperature unit is Fahrenheit.
 
 ```go 
 temperatureUnit := Celsius
-fmt.Println(temperatureUnit)
-// Output: C 
+celsiusUnit := Celsius
+fahrenheitUnit := Fahrenheit
+
+celsiusUnit.String()
+// => °C
+fahrenheitUnit.String()
+// => °F
+fmt.Sprint(celsiusUnit)
+// => °C
 ```
 
 ## 2. Implement the `Stringer` interface for type  `Temperature`
 
-Temperature values consist of an integer and a temperature unit. They should be formatted as in the example below: 
+Temperature values consist of an integer and a temperature unit. They should be formatted as in the examples below.
+
+For that to happen, make the `Temperature` type implement the `Stringer` interface by adding a `String` method to it. This method should return a string with the numeric value for the temperature and the temperature unit separated by a space: `<temperature> <unit>`:
+
 
 ```go
-temperature := Temperature{21, Celsius}
-fmt.Println(temperature) 
-// Output: 21 °C
+celsiusTemp := Temperature{
+    degree: 21,
+    unit: Celsius,
+}
+celsiusTemp.String()
+// => 21 °C
+fmt.Sprint(celsiusTemp)
+// => 21 °C
+
+fahrenheitTemp := Temperature{
+    degree: 75,
+    unit: Fahrenheit,
+}
+fahrenheitTemp.String()
+// => 75 °F
+fmt.Sprint(fahrenheitTemp) 
+// => 75 °F
 ```
 
 ## 3. Implement the `Stringer` interface for type `SpeedUnit`
 
-After lengthy discussions, thee team has agreed that the unit of wind speed will be either `KmPerHour` or `MilesPerHour`. Values should be formatted as shown below: 
+After lengthy discussions, the team has agreed that the unit of wind speed will be either `KmPerHour` or `MilesPerHour`. Values should be formatted as the examples below.
+
+For that to happen, make the `SpeedUnit` type implement the `Stringer` interface by adding a `String` method to it. This method must return the string `"km/h"` if the speed unit is kilometers per hour or `"mph"` if the speed unit is miles per hour:
+
 
 ```go 
-speedUnit := MilesPerHour
-fmt.Println(speedUnit)
-// Output: mph
+mphUnit := MilesPerHour
+mphUnit.String()
+// => mph
+fmt.Sprint(mphUnit)
+// => mph
+
+kmhUnit := KmPerHour
+kmhUnit.String()
+// => km/h
+fmt.Sprint(mphUnit)
+// => km/h
 ```
 
 ## 4. Implement the `Stringer` interface for `Speed` 
 
-Wind speed values consist of an integer and a speed unit. They should be formatted as in the example below: 
+Wind speed values consist of an integer and a speed unit. They should be formatted as in the example below.
+
+For that to happen, make the `Speed` type implement the `Stringer` interface by adding a `String` method to it. This method should return a string with the numeric value for the speed and the speed unit separated by a space: `<speed> <unit>`:
 
 ```go 
-windSpeed := Speed{18, KmPerHour}
-fmt.Println(windSpeed)
-// Output: 18 km/h
+windSpeedNow := Speed{
+    magnitude: 18,
+    unit: KmPerHour,
+}
+windSpeedNow.String(windSpeedNow)
+// => 18 km/h
+fmt.Sprintf(windSpeedNow)
+// => 18 km/h
+
+windSpeedYesterday := Speed{
+    magnitude: 22,
+    unit: MilesPerHour,
+}
+windSpeedYesterday.String(windSpeedYesterday)
+// => 22 mph
+fmt.Sprint(windSpeedYesterday)
+// => 22 mph
 ```
 
 ## 5. Implement the `Stringer` interface for type `MetData`
 
 Meteorological data specifies location, temperature, wind direction, wind speed
-and humidity. It should be formatted as in the example below: 
+and humidity. It should be formatted as in the example below:
+
+For that to happen, make the `MeteorologyData` type implement the `Stringer` interface by adding a `String` method to it. This method should return the meteorology data in the following format: `"<location>: <temperature>, Wind <wind_speed> at <wind_direction>, <humidity>% Humidity"`:
 
 ```go 
-metData := MetData{"San Francisco", Temperature{57, Fahrenheit}, "NW", Speed{19, MilesPerHour}, 60}
-fmt.Println(metData) 
-// Output: San Francisco: 57 °F, Wind NW at 19 mph, 60% Humidity
+sfData := MeteorologyData{
+    location: "San Francisco",
+    temperature: Temperature{
+        degree: 57,
+        unit: Fahrenheit
+    },
+    windDirection: "NW",
+    windSpeed: Speed{
+        magnitude: 19,
+        unit: MilesPerHour
+    },
+    humidity: 60
+}
+
+sfData.String()
+// => San Francisco: 57 °F, Wind NW at 19 mph, 60% Humidity
+fmt.Sprint(sfData) 
+// => San Francisco: 57 °F, Wind NW at 19 mph, 60% Humidity
 ```