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ElementAccess: streamline error cases

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My understanding is that in the standard use case, we precisely know what to expect
and just go ahead and perform the conversion. Thus it is pointless to introduce
fine grained distinctions. When the access fails, this always indicates some broken
application logic, and just raises an error.
This commit is contained in:
Fischlurch 2018-04-13 03:29:08 +02:00
parent ac4f0bc6db
commit 22f50b1b00
2 changed files with 7 additions and 12 deletions
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16
src/gui/model/element-access.hpp
View file

@ -151,7 +151,7 @@ namespace model {
struct ElementAccess::TypeConverter
: RawResult::Visitor
{
Result<TAR&> result;
Result<TAR&> result{"not convertible"};
template<typename X>
using canCast = std::is_convertible<TAR*, X>;
@ -163,6 +163,8 @@ namespace model {
{
if (pb)
result = *dynamic_cast<TAR*> (pb);
else
result = "access returns empty answer";
}
};
@ -175,10 +177,9 @@ namespace model {
* @tparam TAR type of result element expected at the designated location
* @return suitably converted direct (language) reference to the desired element
* wrapped as _result proxy_
* @throw error::Invalid when the designated element exists, but is not
* type or conversion compatible to the expected result type
* @note when access was not possible because the element does not exist,
* the result proxy is empty and convertible to `bool(false)`
* @note when access was not possible because either the element does not exist,
* or is not convertible to the desired target type, the result proxy is empty
* and convertible to `bool(false)`
*/
template<class TAR>
inline ElementAccess::Result<TAR&>
@ -201,10 +202,7 @@ namespace model {
TypeConverter<TAR> converter;
RawResult targetElm = performAccessTo (destination, limitCreation);
targetElm.accept (converter);
if (converter.result.isValid())
return converter.result;
else
return "In current UI, there is no element at location "+string(destination);
return converter.result;
}

3
tests/gui/ctrl/element-access-test.cpp
View file

@ -124,9 +124,6 @@ namespace test {
fakeDirectory->expectedQuery = location;
fakeDirectory->expectedAnswer = &dummyTab;
DummyWidget* duf = &dummyTab;
model::Tangible* luf{duf};
static_assert (std::is_convertible<DummyWidget*, model::Tangible*>::value, "lalü");
AccessAPI accessAPI;
auto answer = accessAPI().access<DummyWidget> (location);