The following code:
typedef void HELPER;
const HELPER* helper = _helper;
inline ostream& operator <<(ostream& out, const HELPER* arg)
{ out << (const char*)(arg); return out; }
Blows up if I attempt a
cout << helper;
Specifically, I get:
main.cpp:35:28: error: use of overloaded operator '<<' is ambiguous (with operand types 'basic_ostream >' and 'const HELPER *' (aka 'const void *'))
and it lists a few candidates:
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/ostream:207:0: note: candidate function
basic_ostream& operator<<(const void* __p);
^
main.cpp:25:17: note: candidate function
inline ostream& operator <<(ostream& out, const HELPER* arg)
^
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/ostream:195:20: note: candidate function
basic_ostream& operator<<(bool __n);
^
I'm a little surprised that my typedef isn't invoking a stronger type matching here. How can I get this operator overload running?
EDIT: Further clarification, the purpose of this code is that I am dual-targeting a set of Arduino libraries. They manage their strings frequently with:
typedef void __FlashStringHelper;
void showHelp(const __FlashStringHelper* helpText)
{
Serial.print(helpText);
}
I like iostream and planned on this dual target, so I overloaded << on Serial object and made the previous into (this is the oversimplified version, for example)
#define cout Serial
void showHelp(const __FlashStringHelper* helpText)
{
cout << helpText;
}
Now I want to actually target real iostream for a different arch, but the old Arduino code can't vary (much) from its __FlashStringHelpers. That's where I'm at
typedef doesn't create types it aliases them,
inline ostream& operator <<(ostream& out, const HELPER* arg)
is equivalent to
inline ostream& operator <<(ostream& out, const void* arg)
Maybe you wanted to create a type named HELPER
class HELPER{};
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