std.exception.enforce - multiple declarations

Prototype

T enforce(E, T)(
  T value,
  const(char)[] msg = null,
  string file = __FILE__,
  size_t line = __LINE__
)
if (is(typeof(()
{
if (!value)
{
}
}
)));

Parameters

Returns

value, if !value is false. Otherwise, new Exception(msg) is thrown.

Note

enforce is used to throw exceptions and is therefore intended to aid in error handling. It is not intended for verifying the logic of your program. That is what assert is for. Also, do not use enforce inside of contracts (i.e. inside of in and out blocks and invariants), because they will be compiled out when compiling with -release. Use assert in contracts.

Example

auto f = enforce(fopen("data.txt"));
auto line = readln(f);
enforce(line.length, "Expected a non-empty line.");

Prototype

T enforce(T, Dg, string file, ulong line)(
  T value,
  Dg dg
)
if (isSomeFunction!Dg && is(typeof(dg())) && is(typeof(()
{
if (!value)
{
}
}
)));

Parameters

Returns

value if !value is false. Otherwise, the given delegate is called.

The safety and purity of this function are inferred from Dg's safety and purity.

Prototype

T enforce(T)(
  T value,
  Throwable ex
);

Parameters

Returns

value if !value is false. Otherwise, ex is thrown.

Example

auto f = enforce(fopen("data.txt"));
auto line = readln(f);
enforce(line.length, new IOException); // expect a non-empty line