# Chatterino pedantic extra guidelines

These guidelines are more specialized and are not included in the main document is spirit of keeping it short and easy to read.

Pure functions
------
Pure functions are easy to reason about since they produce the same output every time they get the same input and don't produce side effects.

###### **example.hpp**

class FilterView : public QWidget
{
    // constructor, etc...
     
    void setFiltered(const std::vector<Item> &items);
    
private:
    std::vector<Item> items_;
}

###### **example.cpp**

#include "example.hpp"

namespace {
    std::vector<Item> filterItems(const std::vector<Item> &items)
    {
        std::vector<Item> items;
    
        // Insert complicated filter function here.
        
        return items;
    }
} // namespace

void FilterView::setFiltered(const std::vector<Item> &items)
{
    // Now we don't have to reason if `setFiltered` has any side effects!
    // We can also reuse `filterItems` later easily.
    this->items_ = filterItems(items);
}