Testing if a function is defined in a module

[Frits van Bommel]

Tyler Knott wrote:
> Kirk McDonald wrote:
>> Carlos Smith wrote:
>>> How can i test (statically), later in the module
>>> if that function have been defined ?
>>
>> There are a few ways of phrasing this, but here's one:
>>
>> static if (is(typeof(&YYUSERINIT))) {
>>     // Do stuff with the function
>> }
> 
> Thanks for the solution.  I was grappling with a similar problem 
> myself.  Would you mind explaining why this works?  I'm a bit fuzzy on 
> IsExpression syntax. I'm guessing it's because you can't take the type 
> of an undeclared symbol, making the Type invalid and the IsExpression 
> return 0, correct?

In this case it's taking the type of an expression that tries to take 
the address of an undefined symbol (note the &), but other than that 
your guess is right.