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X : T := T'Value (S);Case-insensitive conversion of trimmed string S to enumeration type T. Constraint_Error is raised otherwise.
using namespace std::literals;
enum T {
case_0,
case_1,
case_2,
case_4 = 4
};
std::optional<T> TryStrToEnum(std::string_view s) {
if (str == "case_0"sv) return case_0;
if (str == "case_1"sv) return case_1;
if (str == "case_2"sv) return case_2;
if (str == "case_4"sv) return case_4;
return std::nullopt;
}Is case sensitive.
Returns std::nullopt if the conversion fails.
Requires C++17.
Returns std::nullopt if the conversion fails.
Requires C++17.
static class StringToEnum {
static bool TryStrToEnum<T>(
string s, [NotNullWhen(true)] out T? eOut) where T : Enum {
bool success = Enum.TryParse(typeof(T).GetType(), s, out var o);
eOut = (T?)o;
return success;
}
}Conversion is case sensitive.
If fails, return false.
If fails, return false.
T.values.byName(s);No function necessary
conversion is case sensitive
throw an exception if the converstion fails
conversion is case sensitive
throw an exception if the converstion fails
def try_str_to_enum(t, string), do: t[string]Conversion is case-sensitive.
Failing conversation returns nil.
Failing conversation returns nil.
T x = T.valueOf(s);Case sensitive.
Throws java.lang.IllegalArgumentException in case of no match.
Throws java.lang.IllegalArgumentException in case of no match.
function TryEnumToStr(const s: string; out enum: T): Boolean;
var
code: integer;
begin
Val(s, enum, code);
Result := (code = 0);
end;Conversion is case insensitive.
Returns true if the conversion succeeds, false otherwise.
Returns true if the conversion succeeds, false otherwise.
my %T = ( RED => 1, GREEN => 2, BLUE => 3 );
sub TryStrToEnum { my $s = shift; $T{uc $s} }
print GREEN; # prints 2
print TryStrToEnum('BLUE'); prints 3
Perl is not a strictly typed language and has no builtin enum. One approach is to use a hash (similar to a Python map) -- but it won't catch a name misspelling at compile time error. See 'use constant' and CPAN's 'enum' for better options. This implementation is case insensitive, courtesy of uc (uppercase). Conversion failure returns undef.
use constant { RED => 1, GREEN => 2, BLUE => 3 };
sub TryStrToEnum { eval uc shift }
say GREEN; # prints 2
say TryStrToEnum('BLUE'); # prints 3Perl is not a strictly typed language and has no builtin enum. The nearest equivalent is 'use constant', which can be used to define names that can be used like constants. Under the covers they are actually subroutines which return the associated value. There are also CPAN routines (like 'enum') which provide more flexibility. This implementation is case insensitive, courtesy of uc (uppercase). Conversion failure returns undef.
t = T[s]No function necessary.
Conversion is case-sensitive.
Failing conversion raises an exception.
Conversion is case-sensitive.
Failing conversion raises an exception.
enum MyEnum {
Foo,
Bar,
Baz,
}
impl FromStr for MyEnum{
type Err = String;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s.to_lowercase().as_str() {
"foo" => Ok(MyEnum::Foo),
"bar" => Ok(MyEnum::Bar),
"baz" => Ok(MyEnum::Baz),
_ => Err("Could not convert str to enum".to_string())
}
}
}
Err could be an anyhow error or a custom struct
Alternatively use EnumString macro from strum crate.
Alternatively use EnumString macro from strum crate.