Constructor
<boost/url/param.hpp>
template<class OptionalString>
param_pct_view(
    pct_string_view key,
    OptionalString const& value);
This constructs a parameter with a key and optional value, which may both contain percent escapes.
The new key and value reference the same corresponding underlying character buffers.
Ownership of the buffers is not transferred; the caller is responsible for ensuring that the assigned buffers remain valid until they are no longer referenced.
param_pct_view qp( "key", optional<core::string_view>("value") );
this->key.data() == key.data() && this->value->data() == value->data() && this->has_value == true
Linear in key.size() + value->size().
Exceptions thrown on invalid input.
| Name | Thrown on | 
|---|---|
| system_error | keyorvaluecontains an invalid percent-encoding. | 
| Name | Description | 
|---|---|
| OptionalString | An optional core::string_viewtype, such asboost::optional<core::string_view>orstd::optional<core::string_view>. | 
| Name | Description | 
|---|---|
| key | The key to set. | 
| value | The optional value to set. |