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Copy pathfunction.cpp
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168 lines (121 loc) · 4.33 KB
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// # function
#include "common.hpp"
// TODO factor those dummy classes.
class Class {};
class Base {};
class BaseProtected {};
// Default args. C++ only.
// Creates several name mungled functions on the assembly code.
int DefaultArgs(int i, int j=0) { return i + j; }
// ERROR: Cannot use one argument as the default for the other.
//int DefaultArgs(float f, float f2=f) { return f + f2; }
// ERROR: no compound literals in c++
//void foo (int bar[] = (int[2]){0 ,1});
// Function overloading
std::string overload(int i) { return "i"; }
std::string overload(float i) { return "f"; }
std::string overload(int i, int j) { return "ii"; }
std::string overload(float i, float j, float k = 0.f) { return "iff"; }
// OK even if return type is different all is decided at compile time.
//int overload(int i, int j, int k){return 1;}
// ERROR: conflict with int.
//void overload(const int i){}
// ERROR: cannot differentiate by output since output is used to decide if other parts of code make sense.
//int overload(){return 0;}
//float overload(){return 0.f;}
// ERROR: conflict with int int
//void overload(int i, int j=0){cout << "int int=";}
// BAD: compiles, but is useless to give a default,
// since when calling, caller is *forced* to give a value for j
// or wil get `call is ambiguous` compile time error
// because compiler cannot decide between
// here the default arg can be usefull for a call of type float float.
//void overload(float i, float j=1){cout << "float float=";}
// TODO: why does this compile, that is, how not to make an ambiguous call with overload(int).
void overloadValAddr(const int i) {}
void overloadValAddr(const int& i) {}
void overloadBase(Base b) {}
void overloadBase(BaseProtected b) {}
// Default arguments.
void defaultArgProto(int i=0);
void defaultArgProto(int i) {}
// BAD: usually not what you want
// since includers will not see the default version
void defaultArgDef(int i);
void defaultArgDef(int i=0) {}
// ERROR: default cannot go in declaration and definition
//void defaultArgBoth(int i=0);
//void defaultArgBoth(int i=0) {}
int def_no_argname(int) { return 1; }
int def_no_argname(int, int) { return 2; }
/*
# auto arguments
*/
/*ERROR: no you can't*/
/*
int func_auto(auto a){
++a;
return (int)a;
}
*/
int main() {
// # Overload
{
assert(overload(1) == "i");
//base type conversions
{
assert(overload(1.0f) == "f");
/*
ERROR: ambiguous overload(int) overload(float)
Compiler does not know wether convert double to float or int.
*/
//overload(1.0);
}
/*
ERROR: ambiguous
should compiler coverts to Base or BaseProtected? Both are possible via the default copy constructors.
*/
{
Class cOverload;
//overloadBase(cOverload);
}
// ERROR: ambiguous
//i=4;
//overloadValAddr(i);
// # Default arguments
{
assert(DefaultArgs(1) == 1);
assert(DefaultArgs(1, 1) == 2);
}
/*
# Default arguments for references
There seems to be no standard way of doing that without using extra memory / verbosity.
http://stackoverflow.com/questions/2816293/passing-optional-parameter-by-reference-in-c
*/
/*
# volatile overload
Functions that differ by `volatile` can be overloaded:
- http://stackoverflow.com/questions/10242578/volatile-overloading
*/
{}
/*
Function pointer: decided by the typecast.
http://stackoverflow.com/questions/2942426/how-to-specify-a-pointer-to-an-overloaded-function
*/
{
// Variable.
{
std::string (*fi)(int) = overload;
std::string (*ff)(float) = overload;
}
}
}
/*
In C++, unlike in C, definitions can omit argument names if they don't use those arguments!
This probably exists for method overridding.
*/
{
assert(def_no_argname(0) == 1);
assert(def_no_argname(0, 0) == 2);
}
}