Categories: functors, adaptors Component type: type

### Description

Binary_compose is a function object adaptor. If f is an Adaptable Binary Function and g1 and g2 are both Adaptable Unary Functions, and if g1's and g2's return types are convertible to f's argument types, then binary_compose can be used to create a function object h such that h(x) is the same as f(g1(x), g2(x)). [1] [2]

### Example

Finds the first element in a list that lies in the range from 1 to 10.
list<int> L;
...
list<int>::iterator in_range =
find_if(L.begin(), L.end(),
compose2(logical_and<bool>(),
bind2nd(greater_equal<int>(), 1),
bind2nd(less_equal<int>(), 10)));
assert(in_range == L.end() || (*in_range >= 1 && *in_range <= 10));

Computes sin(x)/(x + DBL_MIN) for each element of a range.

transform(first, last, first,
compose2(divides<double>(),
ptr_fun(sin),
bind2nd(plus<double>(), DBL_MIN)));

### Definition

Defined in the standard header functional, and in the nonstandard backward-compatibility header function.h. The binary_compose class is an SGI extension; it is not part of the C++ standard.

### Template parameters

Parameter Description Default
AdaptableBinaryFunction The type of the "outer" function in the function composition operation. That is, if the binary_compose is a function object h such that h(x) = f(g1(x), g2(x)), then AdaptableBinaryFunction is the type of f.
AdaptableUnaryFunction1 The type of the first "inner" function in the function composition operation. That is, if the binary_compose is a function object h such that h(x) = f(g1(x), g2(x)), then AdaptableBinaryFunction is the type of g1.
AdaptableUnaryFunction2 The type of the second "inner" function in the function composition operation. That is, if the binary_compose is a function object h such that h(x) = f(g1(x), g2(x)), then AdaptableBinaryFunction is the type of g2.

### Members

Member Where defined Description
argument_type Adaptable Unary Function The type of the function object's argument: AdaptableUnaryFunction::argument_type.
binary_compose See below.
binary_compose See below.

### New members

These members are not defined in the Adaptable Unary Function requirements, but are specific to binary_compose.
Member Description
The constructor. Constructs a binary_compose object such that calling that object with the argument x returns f(g1(x), g2(x)).