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use v6;
use Test;
plan 21;
# L<S04/"Phasers"/once "runs separately for each clone">
{
is(EVAL(q{{
my $str;
for 1..2 {
my $sub = {
once { $str ~= $_ };
};
$sub();
$sub();
}
$str;
}}), '12');
};
# L<S04/"Phasers"/once "puts off" initialization till
# "last possible moment">
{
my $var;
my $sub = sub ($x) { once { $var += $x } };
nok $var.defined, 'once {...} has not run yet';
$sub(2);
is $var, 2, 'once {} has executed';
$sub(3);
is $var, 2, "once {} only runs once for each clone";
}
# L<S04/"Phasers"/once "on first ever execution">
{
my $str ~= 'o';
{
once { $str ~= 'i' }
}
is $str, 'oi', 'once {} runs when we first try to use a block';
}
# L<S04/"Phasers"/once "executes inline">
# Execute the tests twice to make sure that once binds to
# the lexical scope, not the lexical position.
for <first second> {
my $sub = {
my $str = 'o';
once { $str ~= 'I' };
once { $str ~= 'i' };
":$str";
};
is $sub(), ':oIi', "once block set \$str to 3 ($_ time)";
is $sub(), ':o', "once wasn't invoked again (1-1) ($_ time)";
is $sub(), ':o', "once wasn't invoked again (1-2) ($_ time)";
}
# Some behavior occurs where once does not close over the correct
# pad when closures are cloned
my $ran;
for <first second> {
my $str = 'bana';
$ran = 0;
my $sub = {
once { $ran++; $str ~= 'na' };
};
$sub(); $sub();
is $ran, 1, "once block ran exactly once ($_ time)";
is $str, 'banana', "once block modified the correct variable ($_ time)";
}
# L<S04/"Phasers"/once "caches its value for all subsequent calls">
{
my $was_in_once;
my $sub = {
my $var = once { $was_in_once++; 23 };
$var //= 42;
$var;
};
nok $was_in_once.defined, 'once {} has not run yet';
is $sub(), 23, 'once {} block set our variable (2)';
#?niecza todo
is $sub(), 23, 'the returned value of once {} still there';
is $was_in_once, 1, 'our once {} block was invoked exactly once';
}
# Test that once {} blocks are executed only once even if they return undefined
# (the first implementation ran them twice instead).
{
my $was_in_once;
my $sub = { once { $was_in_once++; Mu } };
nok $sub().defined, 'once {} returned undefined';
$sub();
$sub();
is $was_in_once, 1,
'our once { ...; Mu } block was invoked exactly once';
}
# vim: ft=perl6
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