mcpp | Fork of mcpp , a C/C preprocessor

Say I have the following basic CMakeLists.txt file.

SparkNotes:

I'm pulling in a crime API to see hotspots. Certain crimes will not be logged with a lat/long, therefore, are not shown up in standard (free) crime apps.

• Lat/Long pins I've overridden to a new lat/long don't show up on first load/or at all. (google-maps-react) (Confirmed lat/long is valid per crimes in near areas.)
• Normal pins that had an existing lat/long show up fine/show up as soon as it loads. (Even though it's all the same array of data.)
• I loop through the blank lat/long and replace the lat/long with a rough lat/long of the area just so it shows up. In my console log I can confirm that I've overriden the blank lat/long.
• I want these records to understand the neighborhoods/potentially avoid moving into a hotspot of specific crimes.

API Normal:
https://data.seattle.gov/resource/tazs-3rd5.json?$limit=20000&$offset=20000&$order=offense_id

Specific Items: https://data.seattle.gov/resource/tazs-3rd5.json?$where=report_number%20in(%272020-022388%27,%272020-044620%27,%272020-043813%27,%272020-029645%27,%272020-901621%27)

Full Use Case (Which doesn't work for at all pins): https://data.seattle.gov/resource/tazs-3rd5.json?crime_against_category=PERSON&mcpp=MAGNOLIA&offense_parent_group=SEX%20OFFENSES

Request for help: Can someone please help on how to get these overridden pins to show up consistently?

Things I've Tried: Force update/having multiple refreshes etc/decreasing async time. Those work for when I put in specific crime report number, but if I search for kidnapping/peeping tom, they will not pull with the rest of the person crimes.

I can confirm that if I just load every crime in that API, the map logs all of them (except the ones I need), It's like a pin per foot of street, but the pins in the categories I need don't show up. (So I don't believe it's a volume issue.)

Code for API Data:

Consider the following code where the Writer_I acts as an interface. Other classes which fulfil the contract of writing element types in correct form can derive from it. Here, printf and streams are chosen as policies, and Calculator as user.

That interface is somehow stored in Calculator and write_i hides all the ugly details of templates so that class member functions remain clean. Most things remain known at compile time, and inline-able.

I know this is a classic case of virtual + derivation based polymorphism where a non-templated interface can be stored inside Calculator and write member function is called. But having known the type at compile time, and still deferring resolution to run time seems bad. It hints that some run time value will affect the chosen method of writing while that is not the case.

One way could be to make Calculator a template and keep its implementation in a cpp file and include the cpp file in tests. That's just nasty. Every method of Calculator will have a useless template <> on the top. And it's getting instantiated only once. (Twice if you could tests, but then if the only reason to make Calculator a template was tests, I'd say that tests are being too intrusive.)

I saw the talk https://www.youtube.com/watch?v=mU_n_ohIHQk (Meta Polymorphism - Jonathan Boccara - Meeting C++ 2020 Opening Keynote) https://meetingcpp.com/mcpp/slides/2020/meta_polymorphism_pdf3243.pdf

which showed a technique with std::any (which will store the Writer_I instance reference) + lambda (which contains the actual Impl type) + function pointer (which can be called later). Slides 79-83. I tried but got stuck real quick: How to have a function pointer to a generic lambda?

My solution, after all these futile attempts out of curiosity, would be to use iterator pattern and free the Calculator from the responsibility of "writing". Calculator should just be calculating data, not writing it. That solves the problem! Caller gets the data by running iterator++ and writes it any way it likes. Or may not even write it, but just test the numbers directly. Calculator remains a non template, thus in cpp files.

But if there's any way to achieve what I intend with the current design, I'd be happy to see it. I know there are some contradictory constraints, like using type erasure which may internally use virtual but curiosity is allowed on Stack Overflow, right (; ?

https://godbolt.org/z/W74833

EDIT: to clarify, here the user class is Calculator which should not be a template. All writers can remain in headers and need not be hidden. For CRTP, it is actually needed in main to know what each writer implementation does.

I am developing an Android app that works with Android Bluetooth LE. I was testing mostly on the newer devices with API 27 and above. The connection worked just fine. I was able to scan and connect to advertising devices.

Recently, I got a chance to test on Android 6.0 and Android 6.0.1 and things went south. I got the runtime exception with BluetoothGattCharacteristic and I am unsure why its not able to amrshal the value just for Android 6.0 and 6.0.1

I am handling some BLE notifications with a BroadcastReceiver which I am registering and unregistering at the right lifecycle callbacks.