Course of Raku / Advanced / Containers / Scalar containers / Exercises / Default discount

Solution: Default discount

Here is a possible solution to the task.

Code

my $discount is default(0);
say $discount;

$discount = 15;
say $discount;

🦋 You can find the source code in the file default-discount.raku.

Of course, a simpler solution would be to directly initialise the variable with 0:

my $discount = 0;
say $discount;

$discount = 15;
say $discount;

Output

0
15

Comments

1. The is default(0) trait gives the container a value to fall back to while it has not been assigned anything. Reading the variable returns 0, and, unlike an undeclared default, it produces no uninitialized value warning.

2. After the assignment, the container holds 15, and the default no longer plays any role.

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