<h2><code>ui.util.keep_item</code> / <code>ui.util.pop_items</code></h2>

<div class="theming-example">
    <p>
        This pair of function stores and returns arbitrary data during the
        request. It's similar to flash messages, but can store any kind of data
        and removes data after request is finished.
    </p>

    {%- call ui.util.call(show_example) -%}
        {%- raw %}
            {%- do ui.util.keep_item("random", "a", 1) -%}
            {%- do ui.util.keep_item("random", "b", 2) -%}

            {{ ui.util.pop_items("random") | tojson }}

            {# `c` remains unused and will be dropped after request is finished #}
            {%- do ui.util.keep_item("random", "c", 3) -%}
        {%- endraw %}
    {%- endcall %}
</div>

<div class="theming-example">
    <p>
        Data is stored as 2-dimensional map. The first level defines category,
        the second level contains key of the item. It can be used by <code>ui.util.pop_items</code> which
        accepts either a single argument(category) and returns dictionary with
        all keys for the category, or two arguments(category and key) and
        returns just a single item from the category.
    </p>

    <p>
        Note, in Jinja2 you do not need to declare <code>kwargs</code> inside macro
        signature. Just use variable with name <code>kwargs</code> somewhere inside
        macro code and Jinja2 collect all additional arguments into it implicitly.
    </p>

    {%- call ui.util.call(show_example) -%}
        {%- raw %}
            {%- do ui.util.keep_item("data", "a", 1) -%}
            {%- do ui.util.keep_item("data", "b", 2) -%}
            {%- do ui.util.keep_item("data", "c", 3) -%}


            C is {{ ui.util.pop_items("data", "c") }}.

            The rest if {{ ui.util.pop_items("data") | tojson }}
        {%- endraw %}
    {%- endcall %}
</div>

<div class="theming-example">
    <p>
        <code>ui.util.pop_items</code> removes the item/category upon
        access. If you want to check the content, but without removing it,
        enable <code>keep</code> flag.
    </p>

    {%- call ui.util.call(show_example) -%}
        {%- raw %}
            {%- do ui.util.keep_item("data", "a", 1) -%}

            Peek: {{ ui.util.pop_items("data", "a", keep=true) }}.
            Pop: {{ ui.util.pop_items("data", "a") }}.
            Now it's empty: {{ ui.util.pop_items("data", "a") }}.

        {%- endraw %}
    {%- endcall %}
</div>