rename String.isEmpty to isNullOrEmpty

[subzero911]

https://pub.dev/documentation/quiver/latest/quiver.strings/isEmpty.html

Because its actual implementation is s == null || s.isEmpty;
Also, it conflicts with Flutter standard library isEmpty function https://api.flutter.dev/flutter/dart-core/String/isEmpty.html which actually does what it says.

The same is applicable to isNotEmpty

[jtmcdole]

Renaming global api, especially old api, is a breaking change. This was pre-null safe code (and pre Dart extensions). I'd suggest just removing it.

[subzero911]

Let's mark it @deprecated
And introduce a new isNullOrEmpty method.
The safiest way.

[cbracken]

Oh wow yeah... this is pretty ancient stuff. Like @jtmcdole says, I'd be tempted to just deprecate it and not replace it. Prior to non-null by default, it was designed to solve usecases such as:

Iterable<String> maybeNonEmptyStrings = ...;
Iterable<String> nonEmptyStrings = maybeEmptyStrings.where(isNotEmpty);

With non-null by default (NNBD) the default behaviour now, and with the generic type of the returned Iterable of where matching the parameter type, this function isn't particularly useful any more in that scenario. This won't compile:

Iterable<String?> maybeNonEmptyStrings = ...;
Iterable<String> nonEmptyStrings = maybeEmptyStrings.where(isNotEmpty);

and this is undesirable:

Iterable<String?> maybeNonEmptyStrings = ...;
Iterable<String?> nonEmptyStrings = maybeEmptyStrings.where(isNotEmpty);

Arguably, with NNBD enabled, where you've got some code where nulls were explicitly permitted, it's better to be explicit about the filter criteria from a readability standpoint, so something like:

Iterable<String> nonEmptyStrings = maybeEmptyStrings
  .whereType<String>()
  .where((a) => a.isNotEmpty);

I'd suggest we just deprecate it and remove it in some future version.