Enable attributes without values

[baloe]

It seems acceptable to also have attributes without values, e.g. the controls attribute for the video tag:
https://www.w3schools.com/html/html5_video.asp

<video controls> ...

Is this possible with dominate? If so I am unable to figure out how.
If not, how about adding a rule that attribute=None is rendered as an attribute without a value?
Right now attribute=None seems to be equivalent to attribute=False which simply prevents the attribute from being rendered at all.

[golightlyb]

Note that

<video controls>

is equivalent to

<video controls="controls">

[Knio]

Other users had requested that attribute=None means it should be interpreted the same as not present at all (same as deleted). See previous issues.

As above, attribute=True results in rendering as attribute="attribute", and the HTML spec enforces that to mean the same thing a present with no value.

[bfricka]

@Knio

Boolean attributes represent their "true" state when present in an element, regardless of whether they have a value. The HTML Living Standard specifies:

If a boolean attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace.

This means both <option selected> and <option selected="selected"> are valid.

The minimized form (<option selected>) is valid and concise. It is the shortest way to express a boolean attribute while preserving its meaning. Browsers interpret both forms equivalently. In my experience (12+ years) most developers and tools favor the minimized form for its simplicity. The selected="selected" style is more verbose and sometimes perceived as redundant.

Adjusting dominate to support the minimized form, though not strictly necessary, could make its output more idiomatic.

You could support a global setting that affects the default rendering behavior (dominate.util.concise_attrs = True). You could have an option in rendering html.render(consise_attrs=True). You could also make it the default and have an inverse modifier for those who like verbose attrs.

Overall, it's not a big deal, but it's also an easy thing to fix, and doing so would align with how most HTML is written and rendered.

[Knio]

I was previously against this because I thought it was not actually part of the spec, also it seemed like the OP was just trying to get it to work at all, and not a bug about particular styles.

In any case, since https://html.spec.whatwg.org/multipage/syntax.html#attributes-2 and https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#boolean-attributes explicitly allow this, I'm happy to change the behavior