Sunday, November 27, 2016
How to name a function - Coding in Style - episode 11
Welcome to Coding in style, a series of short videos about how to improve our code.
This is Dragos and you are watching the Episode number 11 where we talk about how to name functions and function parameters.
A few days ago I met a friend. “What are you doing these days?”, he asked. I replied: “Book”. “What do you mean?” he asked. “Swift 3”. “Are you are reading a book about Swift 3?” he said. “Yes, I do,” I replied. “Why didn’t say so?” he said.
Of course, this is not a real conversation as it would have been a strange one. But sometimes this is how we name our functions.
As we’ve seen in the previous episodes, the variables are the nouns of our code.
Similarly, the functions are the verbs. They show an action.
To check if a function name is good, you can have a chat with it:
“Hey function, whatcha doing?”
And the function should be able to reply:
“I [function name]”
You should be able to include the function name after “I” and make a valid sentence.
Let’s look at some examples:
"I dropDatabase" - yes
"I sortArray" - yes
"I user" - nop
"I database" - nop
"I createDatabase" - yes
"I databaseCreate" - sort of, but only if your name Yoda is
You can pick a capitalization rule and stick to it. For Swift, it is lower camelcase.
So dropDatabase is fine, but not dropDATABASE or drop_database.
This can be a bit weird in the case of a name that includes an abbreviation. For example HTML or HTTP.
For example, do you use formatHTML or formatHtml?
createURL or createUrl.
In my opinion, whatever you choose looks ugly, so just pick one and be consistent.
Be specific. The name should make it clear what is the purpose of the function.
For example, create is not a good one. createDatabase is better
Long names are okay.
Make the names as long as needed, but no longer than that.
For example, if you have a function createLocalDatabase and there is only one database, replace it with createDatabase.
Regarding the function parameters, apply the same rules as for variables. In couple words, the name of a parameter should be a good replacement in the sentence “my name is [parameter name]”.
Regarding the number of parameters, they should be as few as possible.
Here is what Uncle Bob (aka Robert C. Martin) says in his "Clean Code" book:
"The ideal number of arguments for a function is zero (niladic). Next comes one (monadic), followed closely by two (dyadic). Three arguments (triadic) should be avoided where possible. More than three (polyadic) requires very special justification—and then shouldn’t be used anyway."
How about methods? Obviously, we use the same rules.
But, BTW, do you know what is the difference between a function and a method? A method is a function that belongs to a class. So a function is a free bird. A method is a free bird that has been captured and put in a cage, called class.
What else? What are your ideas about naming a function?
That is about it for today. We talked about how to name a function. In a previous episode, more exactly episode 7, we discussed how to name entities in general and in episode 8 we talked about how to name a variable or a constant. Feel free to watch them for more details.
That’s about it for now. See you soon!
Friday, November 11, 2016
Reducing the cyclomatic complexity - Coding in style - Episode 9
Welcome to Coding in style, a series of short videos about how to improve our coding.
This is Dragos and you are watching the Episode number 9 where we talk about how to reduce the complexity of a program.
What if you asked somebody the following question: how can I get to the downtown? And the answer was: You take the bus 102 or 103. If you take the 102, you go for two blocks and get off. Then, if it’s morning, you take 104 bus, if it’s evening and during a weekday you take 105. If it’s weekend you take 106. If you take 104, you get off after 3 blocks, if you take 105 after 5 blocks. Nobody can remember such a thing. But, lots of times, we write code like this.
As you know, the developing process does not end when you finish a task. It does not end when you launch the product or when you fix a bug. It finishes only when the code and the product are trashed and erased from existence. Until then, every little piece of code you write has a big chance to be visited again and changed.
Because of that, it is good idea to write awesome code every step of the way. Do to others as you would have them do to you can be translated, in this case, write your code as you would like others to write the code for you. In a good style, that is.
Maybe one of the most important qualities some code has is to be easy to understand. If nobody can understand our code, it does not mean we are very smart and the code is awesome. No, no, no. On the contrary. It means our brain is so complicated, that we are not able to write simple code.
There is one measure for the complexity of the code. It is called cyclomatic complexity.
The cyclomatic complexity defines the number of possible paths a piece of code can follow. It can be defined for a whole app or for a function.
For example:
//Example 1
func printHello() {
print("Hello")
}
There is only one option of execution, so the complexity is 1.
The following function has complexity 2, as there are two possible paths:
//Example 2
func checkIfTeenager(age:Int) {
if age < 13 {
print("not teenager")
} else {
print("teenager")
}
}
While there is some debate about what complexity should be maximum, it is clear that the smaller the better.
Here are some suggestions to reduce it.
//Example 3
func checkIfPositive(n:Int) -> Bool {
if n > 0 {
return true
} else {
return false
}
}
The function has the complexity 2 as there are two different paths. The more if-s one adds the bigger the complexity is.
We can eliminate the if statement, and thus reducing the complexity, by returning directly the Boolean:
func checkIfPositive1(n:Int) -> Bool {
return (n > 0)
}
//Example 4
func convertToString(n:Int) -> String {
switch n {
case 0:
return "zero"
case 1:
return "one"
case 2:
return "two"
case 3:
return "three"
case 4:
return "four"
case 5:
return "five"
case 6:
return "six"
case 7:
return "seven"
case 8:
return "eight"
case 9:
return "nine"
default:
return "unknown"
}
}
This ugly function has complexity 11. It also has ugliness 1000, but that is not a measure that is invented yet.
What to do?
We can replace the ugly function with:
func convertToString1(n:Int) -> String {
if (n>=0) && (n<=9) {
let numberAsString = ["zero", "one", "two", "three", "four", "five",
"six", "seven", "eight", "nine"]
return numberAsString[n]
} else {
return "unknown"
}
}
In this case, the complexity is down to 2.
Let’s check another example, for formatting an address:
//Example 5
func formatAddress(street: String, city:String, country:String) -> String {
if street == "" {
if city == "" {
if country == "" {
return ""
} else {
return country
}
} else {
if country == "" {
return city
} else {
return city + "," + country
}
}
} else {
if city == "" {
if country == "" {
return street
} else {
return street + "," + country
}
} else {
if country == "" {
return street + "," + city
} else {
return street + "," + city + ", " + country
}
}
}
}
Not only it is a solution that does not look nice, it is also error prone. Also, it is long. And it has the complexity of 8, which is pretty big.
We can reduce the complexity by writing a helper function that just adds a command to an item:
func appendItem(item:String) -> String {
if item == "" {
return ""
} else {
return item + ","
}
}
Then we can format the address by appending all the elements to each other:
func formatAddress1(street: String, city:String, country:String) -> String {
var result = appendItem(item: street)
+ appendItem(item: city)
+ appendItem(item: country)
if result.hasSuffix(",") {
result.remove(at: result.index(before: result.endIndex))
}
return result
}
That is about it for today. We talked about reducing the complexity of the code. While it might seem awesome that one is able to write complex code, the reality is the another way round. The smarter one developer is, the simpler and easier to understood code he writes.
What do you think about the topic? What are the ways you like to simplify your code? Feel free to leave a message to the video or send me an email.
Do you have any idea for a topic, send me a message as well!
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