Write your own methods for objects

Automatically translated from English

A new command is at your disposal allowing you to use formulas in your code. You can now encapsulate them in objects and call them when needed. There’s no more need to write your code as text. Now you can just pass your formula in your command and that’s it! This is a great addition, since your code isn’t text, you can benefit from Syntax highlighting and all the other advanced functionalities of the code editor!

Encapsulate a formula in an object

With the New formula command, it’s very simple to encapsulate a formula in an object:

$f:=New formula(ALERT("Hello world"))

And of course, because the formula is encapsulated in an object, you can encapsulate it in a property of an object and create your own encapsulated object methods:

$f:=New object
$f.message:=New formula(ALERT("Hello world"))
$f.message() // Display alert dialog box with the message "Hello world"

If you want to pass parameters to your formula, just use $1, $2 … as in your methods:

$f:=New object
$f.message:=New formula(ALERT("Hello "+$1))
$f.message("John")
// Display alert dialog box with the message "Hello John"

Or if you want to use the value of an object attribute, the This command is the answer:

$f:=New object
$f.text:="Hello World"
$f.message:=New formula(ALERT(This.text))
$f.message()
// Display alert dialog box with the message "Hello world"

Finally, you can use a method as a formula:

$person:=New object
$person.firstName:="John"
$person.lastName:="Smith"
$person.greeting:=New formula(Greeting )
$g:=$person.greeting("hello")
// $g:="hello John Smith"
$g:=$person.greeting("hi")
// $g:="hi John Smith"

With the Greeting method:

$0:=$1+" "+This.firstName+" "+This.lastName

You can find other examples of how to use New formula in this HDI:

HDI_NewFormula

Calling your formula

You can also execute a formula object without setting it as a property of another object by using the call() and apply() methods.

$f:=New formula(ALERT(String($1+" "+$2))
$f.call(null;"Hello";"world")
$f.apply(null;New collection("Hello";"world") //formula.apply object methods

Encapsulate a formula in an object from a string

There’s a way to use a text version of a formula to create a method with the New formula from string command:

$textFormula:=Request("Please type a formula")
 If(ok=1)
    $f:=New formula from string($textFormula)
    ALERT("Result = "+String($f.call()))
 End if

Fabrice Mainguené

• Product Owner •

Fabrice Mainguené joined 4D Program team in November, 2016. As a Product Owner, he is in charge of writing the user stories then translating it to functional specifications. His role is also to make sure that the feature implementation delivered is meeting the customer need.

After obtaining a Bachelor degree in Computer Science at CNAM, Fabrice joined a small software publishing company as a Windev developer. Then he worked for different companies in industry and trade areas as a Windev and web developer as well as technical advisor on new features.