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[dart/en]Fix bool implicit conversions support.

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Implicit conversions of bool are supported now.
This commit is contained in:
OKry 2018-11-07 14:29:27 +08:00 committed by GitHub
parent 76e5f436df
commit ffc33ee560
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1 changed files with 34 additions and 10 deletions
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@ -176,23 +176,47 @@ example13() {
match(s2);
}
// Boolean expressions need to resolve to either true or false, as no
// implicit conversions are supported.
// Boolean expressions support implicit conversions and dynamic type
example14() {
var v = true;
if (v) {
print("Example14 value is true");
var a = true;
if (a) {
print("true, a is $a");
}
v = null;
a = null;
if (a) {
print("true, a is $a");
} else {
print("false, a is $a"); // runs here
}
// dynamic typed null can be convert to bool
var b;// b is dynamic type
b = "abc";
try {
if (v) {
// Never runs
if (b) {
print("true, b is $b");
} else {
// Never runs
print("false, b is $b");
}
} catch (e) {
print("Example14 null value causes an exception: '${e}'");
print("error, b is $b"); // this could be run but got error
}
b = null;
if (b) {
print("true, b is $b");
} else {
print("false, b is $b"); // runs here
}
// statically typed null can not be convert to bool
var c = "abc";
c = null;
// complie failed
// if (c) {
// print("true, c is $c");
// } else {
// print("false, c is $c");
// }
}
// try/catch/finally and throw are used for exception handling.