816884 - Add Boolean literal

Status: RESOLVED INCOMPLETE

(L20n :: General, defect)

Description

[Zibi Braniecki [:zbraniecki][:gandalf]]

We decided that we need a new literal type - boolean.

It will be used in two scenarios:

 - local attributes may have values of type boolean (_person=True)
 - macros may return booleans (<isBlue {{ True }}>)

The exact syntax proposed is: "True" for true, "False" for false.

Comment 1

[Staś Małolepszy :stas]

(In reply to Zbigniew Braniecki [:gandalf] from comment #0)
>  - local attributes may have values of type boolean (_person=True)

The exact syntax would be:

  <foo "Foo"
    _bar: True
    _baz: False
    quux: "Quux"
  >

The thinking behind this is that we don't want to break the promise we make to the developer that everything they get from the context is a string.  Public attributes can be accessed by the developer, and so they need to be strings.  Local attributes, however, are off-limits.

Additionally, Bool's intended use is to describe language-specific meta-data of the entity.  This kind of information is not symmetric between languages so it makes sense to restrict its use to local attributes only.

>  - macros may return booleans (<isBlue {{ True }}>)

Syntax nit; this should read:

  <isBlue { True }>

Comment 2

[Staś Małolepszy :stas]

"True" and "False" will become reserved keywords.  We decided not to reserve any others (the ideas included None, Null, Nil and Undefined).  I reckon that if needed, we can provide similar functionality with macros in the future, e.g. @exists(entity..non_existing_attr).

Comment 3

[Zibi Braniecki [:zbraniecki][:gandalf]]

(In reply to Staś Małolepszy :stas (traveling until Dec 4) from comment #1)
> (In reply to Zbigniew Braniecki [:gandalf] from comment #0)
> >  - macros may return booleans (<isBlue {{ True }}>)
> 
> Syntax nit; this should read:
> 
>   <isBlue { True }>

Syntax nit; this should read:

<isBlue() { True }>

Comment 4

[Staś Małolepszy :stas]

Haha, you're right :)

Comment 5

[Staś Małolepszy :stas]

(In reply to Staś Małolepszy :stas (traveling until Dec 4) from comment #2)
> [...] we can provide similar functionality with macros in the
> future, e.g. @exists(entity..non_existing_attr).

Bug 817617.

Comment 6

[Staś Małolepszy :stas]

Moving this feature to Next.  It's still possible to use strings to achieve the same thing:

<person "Person"
  _animate: "animate"
>

(or, "yes" or whatever)

Comment 7

[Staś Małolepszy :stas]

This bug is about the old L20n syntax which was replaced by the FTL syntax in spring 2016.