PadBuilder: Move `Option<&str>` pad name into a `name(&str)` function

changed milestone to %0.21.0

mentioned in commit fengalin/gst-plugins-rs@67b290cf

mentioned in commit fengalin/gst-plugins-rs@2940ed28

mentioned in commit fengalin/gst-plugins-rs@b1f3e990

mentioned in commit fengalin/gst-plugins-rs@c3c8a350

While updating gst-plugins-rs with these changes, I noticed that many call sites could be simplified if the Pad inherited its name from its template by default. Use cases which require a specific name could use the builder. What do you think?

OTOH, that would mean we no longer get the default name assignment... But, we could use a generated_name() (or so) on the builder to use the default non-frequent behaviour.

I guess the same holds for GhostPad::with_target.

Not sure, that seems like a potentially confusing change from the C behaviour. Also having this as a default behaviour can easily lead to name conflicts, e.g. if you have a bin with multiple elements and add ghostpads for all the "sink" pads.

Makes sense.

Looks like I accidentally created another gitlab account... That was me answering above.

mentioned in commit fengalin/gst-plugins-rs@1e3d0653

I'm almost done with this changes (including the gst-plugins-rs update). I see variations on the way constructors are named. And I need to add new builder constructors so that all variations can define the optional name. These are the constructors for GhostPad currently:

from_static_template
builder_with_static_template
from_template
builder_with_template
with_target
from_template_with_target

The first 4 suggest a pattern: from_ for the option-less constructors and builder_with_ otherwise. However, constructor based on the target use with_. I get the from_ / with_ distinction for template and target. However, I'm unsure why builders would use with instead. Finally, I'm not sure I would like to add builder_with_template_with_target.

My suggestion would be to use from_ for template and with_ for target, for both the option-less constructors and builders. That would give us: