Document that the :match function for a widget takes an external value
* doc/misc/widget.texi (Basic Types): Document what an external value is. Document that a :match function expects the value to be in the external format. (Bug#8717)
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@ -484,9 +484,21 @@ are interpreted in a widget specific way.
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The following keyword arguments apply to all widgets:
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The following keyword arguments apply to all widgets:
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@table @code
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@table @code
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@cindex internal format
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@cindex external format
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@vindex value@r{ keyword}
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@vindex value@r{ keyword}
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@item :value
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@item :value
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The initial value for widgets of this type.
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The initial value for widgets of this type. Typically, a widget
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represents its value in two formats: external and internal. The
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external format is the value as the rest of Emacs sees it, and the
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internal format is a representation that the widget defines and uses
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in a widget specific way.
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Both formats might be the same for certain widgets and might differ
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for others, and there is no guarantee about which format the value
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stored in the @code{:value} property has. However, when creating a
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widget or defining a new one (@pxref{Defining New Widgets}), the
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@code{:value} should be in the external format.
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@vindex format@r{ keyword}
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@vindex format@r{ keyword}
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@item :format
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@item :format
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@ -629,8 +641,9 @@ representation of the @code{:value} property if not.
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@vindex match@r{ keyword}
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@vindex match@r{ keyword}
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@item :match
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@item :match
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Should be a function called with two arguments, the widget and a value,
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Should be a function called with two arguments, the widget and an
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and returning non-@code{nil} if the widget can represent the specified value.
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external value, and should return non-@code{nil} if the widget can
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represent the specified value.
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@vindex validate@r{ keyword}
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@vindex validate@r{ keyword}
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@item :validate
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@item :validate
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