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Using Nasal functions: Difference between revisions
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Argument passing by value / by reference
Legoboyvdlp (talk | contribs) (→Default values for function arguments: Correct snippet) |
(Argument passing by value / by reference) |
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Also note that the standard arg vector, including its ellipsis form, is no longer available when using a hash to initialize the parameters of a function call. | Also note that the standard arg vector, including its ellipsis form, is no longer available when using a hash to initialize the parameters of a function call. | ||
=== Argument passing by value / by reference === | |||
If you pass an argument to a function you must consider its type (see [[Typeof]]). If you pass a scalar (string, number), it will be passed '''by value''', if you pass a hash or vector, it will be passed '''by reference'''. | |||
This means: | |||
# If you change an argument variable in your function that was passed '''by value''' (copied), the variable outside the function will stay unchanged. | |||
# If you change an argument variable in your function that was passed '''by reference''' (same memory), the value outside the function '''will change'''. | |||
<syntaxhighlight lang="nasal"> | |||
var add1 = func(myScalar) { | |||
myScalar = myScalar + 1; | |||
return myScalar; | |||
} | |||
var set42 = func(myVector) { | |||
myVector[0] = 42; | |||
} | |||
var a = 1; | |||
print(a); | |||
print(add1(a)); # this prints the return value of the function call! | |||
print(a); # variable a outside the function shall be still 1 | |||
var b = [1,2,3]; | |||
print(debug.string(b)); | |||
print(set42(b)); # print the return value which is 42 | |||
print(debug.string(b)); # now b[0] has changed | |||
</syntaxhighlight> | |||
== Nested functions, implicit return == | == Nested functions, implicit return == | ||