That is overloading numeric conversion.

That sub will be called whenever an object is used in a context that expects a number.

That sub will be called whenever an object is used in a context that expects a number.

The only way I can find of having that sub called is by doing int($obj).
Do you have an example of another way ?

On Windows (where sizeof(long) is 4):

C:\>perl -MMath::GMP -le "print int(Math::GMP->new(311) ** 100);"
385227681
[download]

Math::GMPz achieves the same result with:

C:\>perl -MMath::GMPz=":mpz" -le "print Rmpz_get_ui(Math::GMPz->new(31
+1) ** 100);"
385227681

alternatively:

C:\>perl -MMath::GMPz -le "$x = (Math::GMPz->new(311) ** 100) & 429496
+7295; print $x;"
385227681
[download]

though, in this very last example, $x is a Math::GMPz object, not an IV.

Cheers,
Rob

If there were arithmetic operators that were not overloaded, Perl would invoke numeric conversion before using the builtin arithmetic operations, but I expect Math::GMP to overload all of them, so int may be the only built-in that actually invokes the numeric conversion.

I expect (but am not certain) that the '0+' overload is also invoked if an XSUB attempts to convert an object to an IV or UV. This is probably (but I have not traced the code) also how builtin arithmetic operations (which are not used on Math::GMP objects) would end up invoking it.