Requirements helper was introduced to replace plain checks for making them output informative messages (Debug and Verbose mode) and also replace macros REQUIRE_TRUE.
it will lazily evaluate values and messages if the type wrapped and hasgetValue and getMsg methods
it is implicit bool. this makes it usable with logical operators and also inside if conditions. Besides it will benefit from shortcircuit nature of those operators.
there is generic template InfoVariable wrapper for types to make it informative. you can use lambda operators with them as well to make it lazily evaluated
we added custom ShapeInfoVariable wrapper for the NDArray and vector<> shapes to make them informative
one can use expect to add its own proper comparision. simple lambda for that will be like this:
Requirements req1("Requirement Helper Example#1");
int x = 20;
req1.expectLess(x, 22);
req1.expectEq(x, 21); //should fail
Output: Requirement Helper Example#1: {20} expected to be equal to 21
using InfoVariable wrapper
int age = 15;
Requirements req2("Requirement Helper Example#2");
req2.expectGreaterEq(makeInfoVariable(age, "the user's age"), 18);
Output:
Requirement Helper Example#2: the user's age {15} expected to be greater than or equal 18
helper behavior while using many checks in one block
int getAge(){
std::cout<<"getAge() was called"<<std::endl;
return 15;
}
....
Requirements req3("Requirement Helper Example#3");
int z = 20;
req3.expectEq(z, 21);
req3.expectGreaterEq(makeInfoVariable(getAge(), "the user's age"), 18);
Output:
Requirement Helper Example#3: {20} expected to be equal to 21
getAge() was called
As it is seen the second check did not happen as the previous failed. But still getAge() method was called as its function argument.
using shortcircuit to avoid Requirement call at all if the previous one was failed
Requirements req4("Requirement Helper Example#4");
int zz = 20;
req4.expectEq(zz, 21) && //shortcicuit And
req4.expectGreaterEq(makeInfoVariable(getAge(), "the user's age"), 18);
Output:
Requirement Helper Example#4: {20} expected to be equal to 21
using lambdas with InfoVariable. it will make it lazily evaluated
Requirement Helper Example#5: twenty {20} expected to be equal to twenty one 21
6. use bool nature and also log the success case
```cpp
Requirements req6("Requirement Helper Example#6");
NDArray * arr= nullptr;
arr !=nullptr && req6.expectEq(arr->rankOf(), 3) ;
req6.logTheSuccess();
Output:
Requirement Helper Example#6: meets the requirements
custom comparision lambda and also another usage of the custom wrapper written by us ShapeInfoVariable. Note: we will use std::vector<int>. this wrapper can be used with NDArray as well.
terminate called after throwing an instance of 'std::invalid_argument'
what(): Op validation failed
...
Requirement Helper Example#8: {6} expected to be one of these {[1, 2, 3, 7, 8, 9, ]}
Here is live example:
Note: some classes were mocked there and do not represent the exact implementations in libnd4j. https://godbolt.org/z/sq98vchs5