Functions are tasks, type it names, provide parameters and it’ll do it task.
Functions in Green Tea are represented by a at sign followed by the name of the function. The function name is case-sensitive.
Function names follow the same rules as other labels in GreenTea. A valid function name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. As a regular expression, it would be expressed thus: ^[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*$
The very first function you should know is @echo. It print var’s value to screen.
@echo “Hello world!!!”
> Hello world!!!
Declare
@function_name
<block>// the things this function do
Ex:
@my_function
@echo 123
@echo 456
Then you call it
@my_function
> 123456
Adding some parameters, separated by commas:
@say_hi_to $param_1, $param_2
@echo Hello $param_1 I am $param_2
@say_hi_to Annie John
Or:
Annie @say_hi_to Join
> Hello Annie I am John
Functions could return value, when they do, outer code could get the return value
@sum $a, $b
return $a + $b
$sum_total : (@sum 1, 2) + (@sum 3, 4)
> 10
Functions could return multiple values, like Python
@sum $a, $b
return $a + $b, $a – $b
$sum, $sub : (@sum 4, 3)
@echo “$sum and $sub”
> 7 and 1
Note: when using more than 1 function on a line (function and operator, 2 functions,…), you must wrap function call with ()
When you do not have return in your function or have only return with no parameter, function return false.
Regex-name function
Let write a function that add 1 to a number, then write it out.
@add1 $number
@echo ($number + 1)
Now, we need function that add 2 to a number, we will need to write new function which nearly exact content, which is boring. We provide Regular expression function to solve this.
@<function name’s static part>{< function name’s regular expression part>} <parameters>
<actions>
You could use $_func_name to access the value at the regular expression on function name.
Ex:
Let’s rewrite the @addX function.
@add{[0-9]*} $num
@echo( $_func_name + $num)
@add1 2
> 3
@add3 4
> 7
In case that a function call match multi Regex-name functions, only the firstly declared Regex-name function matched will run.