Testing if a function is defined in a module

[Tyler Knott]

Kirk McDonald wrote:
> Carlos Smith wrote:
>> Hi!
>>
>> say i have defined a function (or i dont):
>>
>> int YYUSERINIT( )
>> {
>>    ...
>> }
>>
>>
>> How can i test (statically), later in the module
>> if that function have been defined ?
>>
>> if yes, code using the function will
>> be compiled.
>>
>> Thanks
>>
>>
> 
> 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?